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In `F33f`_`[computer science`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Computer_science]`_`f, `!imperative programming`! is a `F33f`_`[programming paradigm`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Programming_paradigm]`_`f of `F33f`_`[software`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Software]`_`f that uses `F33f`_`[statements`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Statement_(computer_science)]`_`f that change a program's `F33f`_`[state`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=State_(computer_science)]`_`f. In much the same way that the `F33f`_`[imperative mood`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Imperative_mood]`_`f in `F33f`_`[natural languages`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Natural_language]`_`f expresses commands, an imperative program consists of `F33f`_`[commands`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Command_(computing)]`_`f for the `F33f`_`[computer`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Computer]`_`f to perform. Imperative programming focuses on describing `*how`* a program operates step by step (with general order of the steps being determined in `F33f`_`[source code`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Source_code]`_`f by the placement of statements one below the other),`:cite-ref-1[`F5bf`_`[1`#cite-note-1]`_`f] rather than on high-level descriptions of its expected results.

The term is often used in contrast to `F33f`_`[declarative programming`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Declarative_programming]`_`f, which focuses on `*what`* the program should accomplish without specifying all the details of `*how`* the program should achieve the result.`:cite-ref-2[`F5bf`_`[2`#cite-note-2]`_`f]

>>Contents

• `F0af`_`[Procedural programming`#procedural-programming]`_`f

• `F0af`_`[Rationale and foundations of imperative programming`#rationale-and-foundations-of-imperative-programming]`_`f

• `F0af`_`[History of imperative and object-oriented languages`#history-of-imperative-and-object-oriented-languages]`_`f

• `F0af`_`[Examples`#examples]`_`f

• `F0af`_`[Fortran`#fortran]`_`f

• `F0af`_`[COBOL`#cobol]`_`f

• `F0af`_`[Algol`#algol]`_`f

• `F0af`_`[BASIC`#basic]`_`f

• `F0af`_`[C`#c]`_`f

• `F0af`_`[C++`#c]`_`f

• `F0af`_`[See also`#see-also]`_`f

• `F0af`_`[Notes`#notes]`_`f

• `F0af`_`[References`#references]`_`f

-─

>>Procedural programming

`F33f`_`[Procedural programming`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Procedural_programming]`_`f is a type of imperative programming in which the program is built from one or more procedures (also termed `F33f`_`[subroutines`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Subroutine]`_`f or functions). The terms are often used as synonyms, but the use of procedures has a dramatic effect on how imperative programs appear and how they are constructed. Heavy procedural programming, in which `F33f`_`[state`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=State_(computer_science)]`_`f changes are localized to procedures or restricted to explicit arguments and returns from procedures, is a form of `F33f`_`[structured programming`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Structured_programming]`_`f. Since the 1960s, structured programming and `F33f`_`[modular programming`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Modular_programming]`_`f in general have been promoted as techniques to improve the `F33f`_`[maintainability`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Maintainability]`_`f and overall quality of imperative programs. The concepts behind `F33f`_`[object-oriented programming`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Object-oriented_programming]`_`f attempt to extend this approach.

Procedural programming could be considered a step toward declarative programming. A programmer can often tell, simply by looking at the names, arguments, and return types of procedures (and related comments), what a particular procedure is supposed to do, without necessarily looking at the details of how it achieves its result. At the same time, a complete program is still imperative since it `*fixes`* the statements to be executed and their order of execution to a large extent.

>>Rationale and foundations of imperative programming

The programming paradigm used to build programs for almost all computers typically follows an imperative model.`:cite-ref-3[`F5bf`_`[note 1`#cite-note-3]`_`f] Digital computer hardware is designed to execute `F33f`_`[machine code`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Machine_code]`_`f, which is native to the computer and is usually written in the imperative style, although low-level compilers and interpreters using other paradigms exist for some architectures such as `F33f`_`[lisp machines`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Lisp_machine]`_`f.

From this low-level perspective, the program state is defined by the contents of memory, and the statements are instructions in the native machine language of the computer. Higher-level imperative languages use `F33f`_`[variables`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Variable_(programming)]`_`f and more complex statements, but still follow the same paradigm. `F33f`_`[Recipes`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Recipe]`_`f and process `F33f`_`[checklists`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Checklist]`_`f, while not `F33f`_`[computer programs`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Computer_program]`_`f, are also familiar concepts that are similar in style to imperative programming; each step is an instruction, and the physical world holds the state. Since the basic ideas of imperative programming are both conceptually familiar and directly embodied in the hardware, most computer languages are in the imperative style.

`F33f`_`[Assignment statements`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Destructive_assignment]`_`f, in imperative paradigm, perform an operation on information located in memory and store the results in memory for later use. High-level imperative languages, in addition, permit the `F33f`_`[evaluation`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Evaluation_(disambiguation)]`_`f of complex `F33f`_`[expressions`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Expression_(programming)]`_`f, which may consist of a combination of `F33f`_`[arithmetic operations`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Arithmetic]`_`f and `F33f`_`[function`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Function_(mathematics)]`_`f evaluations, and the assignment of the resulting value to memory. Looping statements (as in `F33f`_`[while loops`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=While_loop]`_`f, `F33f`_`[do while loops`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Do_while_loop]`_`f, and `F33f`_`[for loops`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=For_loop]`_`f) allow a sequence of statements to be executed multiple times. Loops can either execute the statements they contain a predefined number of times, or they can execute them repeatedly until some condition is met. `F33f`_`[Conditional`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Conditional_(programming)]`_`f `F33f`_`[branching`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Branch_(computer_science)]`_`f statements allow a sequence of statements to be executed only if some condition is met. Otherwise, the statements are skipped and the execution sequence continues from the statement following them. Unconditional branching statements allow an execution sequence to be transferred to another part of a program. These include the jump (called `*`F33f`_`[goto`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Goto]`_`f`* in many languages), `F33f`_`[switch`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Switch_statement]`_`f, and the subprogram, `F33f`_`[subroutine`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Subroutine]`_`f, or procedure call (which usually returns to the next statement after the call).

Early in the development of `F33f`_`[high-level programming languages`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=High-level_programming_language]`_`f, the introduction of the `F33f`_`[block`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Block_(programming)]`_`f enabled the construction of programs in which a group of statements and declarations could be treated as if they were one statement. This, alongside the introduction of `F33f`_`[subroutines`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Subroutine]`_`f, enabled complex structures to be expressed by hierarchical decomposition into simpler procedural structures.

Many imperative programming languages (such as `F33f`_`[Fortran`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Fortran]`_`f, `F33f`_`[BASIC`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=BASIC]`_`f, and `F33f`_`[C`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=C_(programming_language)]`_`f) are `F33f`_`[abstractions`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Abstraction_(computer_science)]`_`f of `F33f`_`[assembly language`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Assembly_language]`_`f.`:cite-ref-0-4-0[`F5bf`_`[3`#cite-note-0-4]`_`f]

>>History of imperative and object-oriented languages

The earliest imperative languages were the machine languages of the original computers. In these languages, instructions were very simple, which made hardware implementation easier but hindered the creation of complex programs. `F33f`_`[FORTRAN`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=FORTRAN]`_`f, developed by `F33f`_`[John Backus`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=John_Backus]`_`f at `F33f`_`[International Business Machines`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=International_Business_Machines]`_`f (IBM) starting in 1954, was the first major programming language to remove the obstacles presented by machine code in the creation of complex programs. FORTRAN was a `F33f`_`[compiled language`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Compiled_language]`_`f that allowed named variables, complex expressions, subprograms, and many other features now common in imperative languages. The next two decades saw the development of many other major high-level imperative programming languages. In the late 1950s and 1960s, `F33f`_`[ALGOL`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=ALGOL]`_`f was developed in order to allow mathematical algorithms to be more easily expressed and even served as the `F33f`_`[operating system`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Operating_system]`_`f's target language for some computers. `F33f`_`[MUMPS`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=MUMPS]`_`f (1966) carried the imperative paradigm to a logical extreme, by not having any statements at all, relying purely on commands, even to the extent of making the IF and ELSE commands independent of each other, connected only by an intrinsic variable named $TEST. `F33f`_`[COBOL`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=COBOL]`_`f (1960) and `F33f`_`[BASIC`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=BASIC]`_`f (1964) were both attempts to make programming syntax look more like English. In the 1970s, `F33f`_`[Pascal`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Pascal_(programming_language)]`_`f was developed by `F33f`_`[Niklaus Wirth`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Niklaus_Wirth]`_`f, and `F33f`_`[C`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=C_(programming_language)]`_`f was created by `F33f`_`[Dennis Ritchie`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Dennis_Ritchie]`_`f while he was working at `F33f`_`[Bell Laboratories`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Bell_Laboratories]`_`f. Wirth went on to design `F33f`_`[Modula-2`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Modula-2]`_`f and `F33f`_`[Oberon`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Oberon_(programming_language)]`_`f. For the needs of the `F33f`_`[United States Department of Defense`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=United_States_Department_of_Defense]`_`f, `F33f`_`[Jean Ichbiah`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Jean_Ichbiah]`_`f and a team at `F33f`_`[Honeywell`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Honeywell]`_`f began designing `F33f`_`[Ada`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Ada_(programming_language)]`_`f in 1978, after a 4-year project to define the requirements for the language. The specification was first published in 1983, with revisions in 1995, 2005, and 2012.

The 1980s saw a rapid growth in interest in `F33f`_`[object-oriented programming`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Object-oriented_programming]`_`f. These languages were imperative in style, but added features to support `F33f`_`[objects`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Object_(computing)]`_`f. The last two decades of the 20th century saw the development of many such languages. `F33f`_`[Smalltalk`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Smalltalk]`_`f-80, originally conceived by `F33f`_`[Alan Kay`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Alan_Kay]`_`f in 1969, was released in 1980, by the Xerox Palo Alto Research Center (`F33f`_`[PARC`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=PARC_(company)]`_`f). Drawing from concepts in another object-oriented language—`F33f`_`[Simula`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Simula]`_`f (which is considered the world's first `F33f`_`[object-oriented programming language`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Object-oriented_programming_language]`_`f, developed in the 1960s)—`F33f`_`[Bjarne Stroustrup`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Bjarne_Stroustrup]`_`f designed `F33f`_`[C++`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=C++]`_`f, an object-oriented language based on `F33f`_`[C`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=C_(programming_language)]`_`f. Design of `F33f`_`[C++`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=C++]`_`f began in 1979 and the first implementation was completed in 1983. In the late 1980s and 1990s, the notable imperative languages drawing on object-oriented concepts were `F33f`_`[Perl`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Perl]`_`f, released by `F33f`_`[Larry Wall`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Larry_Wall]`_`f in 1987; `F33f`_`[Python`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Python_(programming_language)]`_`f, released by `F33f`_`[Guido van Rossum`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Guido_van_Rossum]`_`f in 1990; `F33f`_`[Visual Basic`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Visual_Basic_(classic)]`_`f and `F33f`_`[Visual C++`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Visual_C++]`_`f (which included `F33f`_`[Microsoft Foundation Class Library`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Microsoft_Foundation_Class_Library]`_`f (MFC) 2.0), released by `F33f`_`[Microsoft`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Microsoft]`_`f in 1991 and 1993 respectively; `F33f`_`[PHP`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=PHP]`_`f, released by `F33f`_`[Rasmus Lerdorf`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Rasmus_Lerdorf]`_`f in 1994; `F33f`_`[Java`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Java_(programming_language)]`_`f, by `F33f`_`[James Gosling`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=James_Gosling]`_`f (`F33f`_`[Sun Microsystems`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Sun_Microsystems]`_`f) in 1995, `F33f`_`[JavaScript`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=JavaScript]`_`f, by `F33f`_`[Brendan Eich`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Brendan_Eich]`_`f (`F33f`_`[Netscape`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Netscape]`_`f), and `F33f`_`[Ruby`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Ruby_(programming_language)]`_`f, by Yukihiro "Matz" Matsumoto, both released in 1995. Microsoft's `F33f`_`[.NET Framework`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=.NET_Framework]`_`f (2002) is imperative at its core, as are its main target languages, `F33f`_`[VB.NET`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=VB.NET]`_`f and `F33f`_`[C#`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=C_Sharp_(programming_language)]`_`f that run on it; however Microsoft's `F33f`_`[F#`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=F_Sharp_(programming_language)]`_`f, a functional language, also runs on it.

>>Examples

>>>Fortran

`F33f`_`[FORTRAN`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=FORTRAN]`_`f (1958) was unveiled as "The IBM Mathematical FORmula TRANslating system." It was designed for scientific calculations, without `F33f`_`[string`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=String_(computer_science)]`_`f handling facilities. Along with `F33f`_`[declarations`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Declaration_(computer_programming)]`_`f, `F33f`_`[expressions`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Expression_(computer_science)]`_`f, and `F33f`_`[statements`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Statement_(computer_science)]`_`f, it supported:

• `F33f`_`[arrays`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Array_data_structure]`_`f

• `F33f`_`[subroutines`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Subroutine]`_`f

• `F33f`_`["do" loops`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=For_loop]`_`f

It succeeded because:

• programming and debugging costs were below computer running costs

• it was supported by IBM

• applications at the time were scientific.`:cite-ref-cpl-3rd-ch2-16-5-0[`F5bf`_`[4`#cite-note-cpl-3rd-ch2-16-5]`_`f]

However, non IBM vendors also wrote Fortran compilers, but with a syntax that would likely fail IBM's compiler.`:cite-ref-cpl-3rd-ch2-16-5-1[`F5bf`_`[4`#cite-note-cpl-3rd-ch2-16-5]`_`f] The `F33f`_`[American National Standards Institute`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=American_National_Standards_Institute]`_`f (ANSI) developed the first Fortran standard in 1966. In 1978, Fortran 77 became the standard until 1991. Fortran 90 supports:

• `F33f`_`[records`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Record_(computer_science)]`_`f

• `F33f`_`[pointers`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Pointer_(computer_programming)]`_`f to arrays

>>>COBOL

`F33f`_`[COBOL`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=COBOL]`_`f (1959) stands for "COmmon Business Oriented Language." Fortran manipulated symbols. It was soon realized that symbols did not need to be numbers, so strings were introduced.`:cite-ref-cpl-3rd-ch2-24-6-0[`F5bf`_`[5`#cite-note-cpl-3rd-ch2-24-6]`_`f] The `F33f`_`[US Department of Defense`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=US_Department_of_Defense]`_`f influenced COBOL's development, with `F33f`_`[Grace Hopper`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Grace_Hopper]`_`f being a major contributor. The statements were English-like and verbose. The goal was to design a language so managers could read the programs. However, the lack of structured statements hindered this goal.`:cite-ref-cpl-3rd-ch2-25-7-0[`F5bf`_`[6`#cite-note-cpl-3rd-ch2-25-7]`_`f]

COBOL's development was tightly controlled, so dialects did not emerge to require ANSI standards. As a consequence, it was not changed for 15 years until 1974. The 1990s version did make consequential changes, like `F33f`_`[object-oriented programming`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Object-oriented_programming]`_`f.`:cite-ref-cpl-3rd-ch2-25-7-1[`F5bf`_`[6`#cite-note-cpl-3rd-ch2-25-7]`_`f]

>>>Algol

`F33f`_`[ALGOL`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=ALGOL]`_`f (1960) stands for "ALGOrithmic Language." It had a profound influence on programming language design.`:cite-ref-cpl-3rd-ch2-19-8-0[`F5bf`_`[7`#cite-note-cpl-3rd-ch2-19-8]`_`f] Emerging from a committee of European and American programming language experts, it used standard mathematical notation and had a readable structured design. Algol was first to define its `F33f`_`[syntax`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Syntax_(programming_languages)]`_`f using the `F33f`_`[Backus–Naur form`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Backus–Naur_form]`_`f.`:cite-ref-cpl-3rd-ch2-19-8-1[`F5bf`_`[7`#cite-note-cpl-3rd-ch2-19-8]`_`f] This led to `F33f`_`[syntax-directed`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Syntax-directed_translation]`_`f compilers. It added features like:

• block structure, where variables were local to their block

• arrays with variable bounds

• `F33f`_`["for" loops`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=For_loop]`_`f

• `F33f`_`[functions`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Subroutine]`_`f

• `F33f`_`[recursion`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Recursion_(computer_science)]`_`f`:cite-ref-cpl-3rd-ch2-19-8-2[`F5bf`_`[7`#cite-note-cpl-3rd-ch2-19-8]`_`f]

Algol's direct descendants include `F33f`_`[Pascal`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Pascal_(programming_language)]`_`f, `F33f`_`[Modula-2`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Modula-2]`_`f, `F33f`_`[Ada`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Ada_(programming_language)]`_`f, `F33f`_`[Delphi`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Delphi_(software)]`_`f and `F33f`_`[Oberon`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Oberon_(programming_language)]`_`f on one branch. On another branch there's `F33f`_`[C`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=C_(programming_language)]`_`f, `F33f`_`[C++`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=C++]`_`f and `F33f`_`[Java`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Java_(programming_language)]`_`f.`:cite-ref-cpl-3rd-ch2-19-8-3[`F5bf`_`[7`#cite-note-cpl-3rd-ch2-19-8]`_`f]

>>>BASIC

`F33f`_`[BASIC`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=BASIC]`_`f (1964) stands for "Beginner's All Purpose Symbolic Instruction Code." It was developed at `F33f`_`[Dartmouth College`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Dartmouth_College]`_`f for all of their students to learn.`:cite-ref-cpl-3rd-ch2-30-9-0[`F5bf`_`[8`#cite-note-cpl-3rd-ch2-30-9]`_`f] If a student did not go on to a more powerful language, the student would still remember Basic.`:cite-ref-cpl-3rd-ch2-30-9-1[`F5bf`_`[8`#cite-note-cpl-3rd-ch2-30-9]`_`f] A Basic interpreter was installed in the `F33f`_`[microcomputers`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Microcomputers]`_`f manufactured in the late 1970s. As the microcomputer industry grew, so did the language.`:cite-ref-cpl-3rd-ch2-30-9-2[`F5bf`_`[8`#cite-note-cpl-3rd-ch2-30-9]`_`f]

Basic pioneered the `F33f`_`[interactive session`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Read–eval–print_loop]`_`f.`:cite-ref-cpl-3rd-ch2-30-9-3[`F5bf`_`[8`#cite-note-cpl-3rd-ch2-30-9]`_`f] It offered `F33f`_`[operating system`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Operating_system]`_`f commands within its environment:

• The 'new' command created an empty slate

• Statements evaluated immediately

• Statements could be programmed by preceding them with a line number

• The 'list' command displayed the program

• The 'run' command executed the program

However, the Basic syntax was too simple for large programs.`:cite-ref-cpl-3rd-ch2-30-9-4[`F5bf`_`[8`#cite-note-cpl-3rd-ch2-30-9]`_`f] Recent dialects added structure and object-oriented extensions. `F33f`_`[Microsoft's`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Microsoft]`_`f `F33f`_`[Visual Basic`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Visual_Basic]`_`f is still widely used and produces a `F33f`_`[graphical user interface`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Graphical_user_interface]`_`f.`:cite-ref-cpl-3rd-ch2-31-10-0[`F5bf`_`[9`#cite-note-cpl-3rd-ch2-31-10]`_`f]

>>>C

`F33f`_`[C programming language`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=C_(programming_language)]`_`f (1973) got its name because the language `F33f`_`[BCPL`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=BCPL]`_`f was replaced with `F33f`_`[B`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=B_(programming_language)]`_`f, and `F33f`_`[AT&T Bell Labs`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Bell_Labs]`_`f called the next version "C." Its purpose was to write the `F33f`_`[UNIX`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=UNIX]`_`f `F33f`_`[operating system`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Operating_system]`_`f.`:cite-ref-cpl-3rd-ch2-37-11-0[`F5bf`_`[10`#cite-note-cpl-3rd-ch2-37-11]`_`f] C is a relatively small language -- making it easy to write compilers. Its growth mirrored the hardware growth in the 1980s.`:cite-ref-cpl-3rd-ch2-37-11-1[`F5bf`_`[10`#cite-note-cpl-3rd-ch2-37-11]`_`f] Its growth also was because it has the facilities of `F33f`_`[assembly language`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Assembly_language]`_`f, but uses a `F33f`_`[high-level syntax`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=High-level_programming_language]`_`f. It added advanced features like:

• `F33f`_`[inline assembler`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Inline_assembler]`_`f

• arithmetic on pointers

• pointers to functions

• bit operations

• freely combining complex `F33f`_`[operators`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Operators_in_C_and_C++]`_`f`:cite-ref-cpl-3rd-ch2-37-11-2[`F5bf`_`[10`#cite-note-cpl-3rd-ch2-37-11]`_`f]

`*C`* allows the programmer to control in which region of memory data is to be stored. `*Global variables`* and `*static variables`* require the fewest `F33f`_`[clock cycles`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Clock_signal]`_`f to store. The `F33f`_`[stack`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Call_stack]`_`f is automatically used for the standard variable `F33f`_`[declarations`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Declaration_(computer_programming)]`_`f. `F33f`_`[Heap`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Manual_memory_management]`_`f memory is returned to a `F33f`_`[pointer variable`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Pointer_(computer_programming)]`_`f from the `F33f`_`[malloc()`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=C_dynamic_memory_allocation]`_`f function.

• The `*global and static data`* region is located just above the `*program`* region. (The program region is technically called the `*text`* region. It's where machine instructions are stored.)

The global and static data region is technically two regions.`:cite-ref-geeksforgeeks-12-0[`F5bf`_`[11`#cite-note-geeksforgeeks-12]`_`f] One region is called the `*initialized `F33f`_`[data segment`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Data_segment]`_`f`*, where variables declared with default values are stored. The other region is called the `*`F33f`_`[block started by segment`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=.bss]`_`f`*, where variables declared without default values are stored. Variables stored in the `*global and static data`* region have their `F33f`_`[addresses`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Memory_address]`_`f set at compile-time. They retain their values throughout the life of the process.

The global and static region stores the `*global variables`* that are declared on top of (outside) the `B100`F9d9main()`f`b function.`:cite-ref-cpl-ch1-p31-13-0[`F5bf`_`[12`#cite-note-cpl-ch1-p31-13]`_`f] Global variables are visible to `B100`F9d9main()`f`b and every other function in the source code.

On the other hand, variable declarations inside of `B100`F9d9main()`f`b, other functions, or within `B100`F9d9{`f`b `B100`F9d9}`f`b `F33f`_`[block delimiters`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Block_(programming)]`_`f are `*local variables`*. Local variables also include `*`F33f`_`[formal parameter`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Parameter_(computer_programming)]`_`f variables`*. Parameter variables are enclosed within the parenthesis of function definitions.`:cite-ref-cpl-3rd-ch6-128-14-0[`F5bf`_`[13`#cite-note-cpl-3rd-ch6-128-14]`_`f] They provide an `F33f`_`[interface`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Interface_(computing)]`_`f to the function.

`*Local variables`* declared using the `B100`F9d9static`f`b prefix are also stored in the `*global and static data`* region.`:cite-ref-geeksforgeeks-12-1[`F5bf`_`[11`#cite-note-geeksforgeeks-12]`_`f] Unlike global variables, static variables are only visible within the function or block. Static variables always retain their value. An example usage would be the function `B100`F9d9int increment_counter(){ static int counter = 0; counter++; return counter;}`f`b

• The `F33f`_`[stack`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Call_stack]`_`f region is a contiguous block of memory located near the top memory address.`:cite-ref-lpi-ch6-p121-15-0[`F5bf`_`[14`#cite-note-lpi-ch6-p121-15]`_`f] Variables placed in the stack are populated from top to bottom.`:cite-ref-lpi-ch6-p121-15-1[`F5bf`_`[14`#cite-note-lpi-ch6-p121-15]`_`f] A `F33f`_`[stack pointer`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Call_stack]`_`f is a special-purpose `F33f`_`[register`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Processor_register]`_`f that keeps track of the last memory address populated.`:cite-ref-lpi-ch6-p121-15-2[`F5bf`_`[14`#cite-note-lpi-ch6-p121-15]`_`f] Variables are placed into the stack via the `*assembly language`* PUSH instruction. Therefore, the addresses of these variables are set during `F33f`_`[runtime`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Runtime_(program_lifecycle_phase)]`_`f. The method for stack variables to lose their `F33f`_`[scope`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Scope_(computer_science)]`_`f is via the POP instruction.

`*Local variables`* declared without the `B100`F9d9static`f`b prefix, including formal parameter variables,`:cite-ref-lpi-ch6-p122-16-0[`F5bf`_`[15`#cite-note-lpi-ch6-p122-16]`_`f] are called `*automatic variables`*`:cite-ref-cpl-ch1-p31-13-1[`F5bf`_`[12`#cite-note-cpl-ch1-p31-13]`_`f] and are stored in the stack.`:cite-ref-geeksforgeeks-12-2[`F5bf`_`[11`#cite-note-geeksforgeeks-12]`_`f] They are visible inside the function or block and lose their scope upon exiting the function or block.

• The `F33f`_`[heap`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Manual_memory_management]`_`f region is located below the stack.`:cite-ref-geeksforgeeks-12-3[`F5bf`_`[11`#cite-note-geeksforgeeks-12]`_`f] It is populated from the bottom to the top. The `F33f`_`[operating system`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Operating_system]`_`f manages the heap using a `*heap pointer`* and a list of allocated memory blocks.`:cite-ref-cpl-ch1-p185-17-0[`F5bf`_`[16`#cite-note-cpl-ch1-p185-17]`_`f] Like the stack, the addresses of heap variables are set during runtime. An `F33f`_`[out of memory`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Out_of_memory]`_`f error occurs when the heap pointer and the stack pointer meet.

`*C`* provides the `B100`F9d9malloc()`f`b library function to `F33f`_`[allocate`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=C_dynamic_memory_allocation]`_`f heap memory.`:cite-ref-cpl-ch8-p187-18-0[`F5bf`_`[17`#cite-note-cpl-ch8-p187-18]`_`f] Populating the heap with data is an additional copy function. Variables stored in the heap are economically passed to functions using pointers. Without pointers, the entire block of data would have to be passed to the function via the stack.

>>>C++

In the 1970s, `F33f`_`[software engineers`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Software_engineering]`_`f needed language support to break large projects down into `F33f`_`[modules`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Modular_programming]`_`f.`:cite-ref-cpl-3rd-ch2-38-19-0[`F5bf`_`[18`#cite-note-cpl-3rd-ch2-38-19]`_`f] One obvious feature was to decompose large projects `*physically`* into separate `F33f`_`[files`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Computer_file]`_`f. A less obvious feature was to decompose large projects `*logically`* into `F33f`_`[abstract`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Abstract_and_concrete]`_`f `F33f`_`[datatypes`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Data_type]`_`f.`:cite-ref-cpl-3rd-ch2-38-19-1[`F5bf`_`[18`#cite-note-cpl-3rd-ch2-38-19]`_`f] At the time, languages supported concrete (`F33f`_`[scalar`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Variable_(computer_science)]`_`f) datatypes like `F33f`_`[integer`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Integer]`_`f numbers, `F33f`_`[floating-point`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Floating-point_arithmetic]`_`f numbers, and `F33f`_`[strings`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=String_(computer_science)]`_`f of `F33f`_`[characters`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Character_(computing)]`_`f. Concrete datatypes have their representation as part of their name.`:cite-ref-stroustrup-ch3-65-20-0[`F5bf`_`[19`#cite-note-stroustrup-ch3-65-20]`_`f] Abstract datatypes are `F33f`_`[structures`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Record_(computer_science)]`_`f of concrete datatypes — with a new name assigned. For example, a `F33f`_`[list`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=List_(abstract_data_type)]`_`f of integers could be called `B100`F9d9integer_list`f`b.

In object-oriented jargon, abstract datatypes are called `F33f`_`[classes`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Class_(computer_programming)]`_`f. However, a `*class`* is only a definition; no memory is allocated. When memory is allocated to a class, it's called an `F33f`_`[object`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Object_(computer_science)]`_`f.`:cite-ref-cpl-3rd-ch8-193-21-0[`F5bf`_`[20`#cite-note-cpl-3rd-ch8-193-21]`_`f]

`*`F33f`_`[Object-oriented imperative languages`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Object-oriented_programming]`_`f`* developed by combining the need for classes and the need for safe `F33f`_`[functional programming`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Functional_programming]`_`f.`:cite-ref-cpl-3rd-ch2-39-22-0[`F5bf`_`[21`#cite-note-cpl-3rd-ch2-39-22]`_`f] A function, in an object-oriented language, is assigned to a class. An assigned function is then referred to as a `F33f`_`[method`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Method_(computer_programming)]`_`f, `F33f`_`[member function`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Method_(computer_programming)]`_`f, or `*`F33f`_`[operation`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Operation_(mathematics)]`_`f`*. `*Object-oriented programming`* is executing `*operations`* on `*objects`*.`:cite-ref-cpl-3rd-ch2-35-23-0[`F5bf`_`[22`#cite-note-cpl-3rd-ch2-35-23]`_`f]

`*Object-oriented languages`* support a syntax to model `F33f`_`[subset/superset`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Subset]`_`f relationships. In `F33f`_`[set theory`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Set_theory]`_`f, an `F33f`_`[element`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Element_(mathematics)]`_`f of a subset inherits all the attributes contained in the superset. For example, a student is a person. Therefore, the set of students is a subset of the set of persons. As a result, students inherit all the attributes common to all persons. Additionally, students have unique attributes that other persons don't have. `*Object-oriented languages`* model `*subset/superset`* relationships using `F33f`_`[inheritance`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Inheritance_(object-oriented_programming)]`_`f.`:cite-ref-cpl-3rd-ch8-192-24-0[`F5bf`_`[23`#cite-note-cpl-3rd-ch8-192-24]`_`f] `*Object-oriented programming`* became the dominant language paradigm by the late 1990s.`:cite-ref-cpl-3rd-ch2-38-19-2[`F5bf`_`[18`#cite-note-cpl-3rd-ch2-38-19]`_`f]

`F33f`_`[C++`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=C++]`_`f (1985) was originally called "C with Classes."`:cite-ref-stroustrup-notes-22-25-0[`F5bf`_`[24`#cite-note-stroustrup-notes-22-25]`_`f] It was designed to expand `F33f`_`[C's`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=C_(programming_language)]`_`f capabilities by adding the object-oriented facilities of the language `F33f`_`[Simula`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Simula]`_`f.`:cite-ref-stroustrup-notes-21-26-0[`F5bf`_`[25`#cite-note-stroustrup-notes-21-26]`_`f]

An object-oriented module is composed of two files. The definitions file is called the `F33f`_`[header file`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Include_directive]`_`f. Here is a C++ `*header file`* for the `*GRADE class`* in a simple school application:

`B100`F9d9// grade.h`f`b

`B100`F9d9// -------`f`b

`B100`F9d9`f`b

`B100`F9d9// Used to allow multiple source files to include`f`b

`B100`F9d9// this header file without duplication errors.`f`b

`B100`F9d9// See: https://en.wikipedia.org/wiki/Include_guard`f`b

`B100`F9d9// ----------------------------------------------`f`b

`B100`F9d9#ifndef GRADE_H`f`b

`B100`F9d9#define GRADE_H`f`b

`B100`F9d9`f`b

`B100`F9d9class GRADE {`f`b

`B100`F9d9public:`f`b

`B100`F9d9 // This is the constructor operation.`f`b

`B100`F9d9 // ----------------------------------`f`b

`B100`F9d9 GRADE ( const char letter );`f`b

`B100`F9d9`f`b

`B100`F9d9 // This is a class variable.`f`b

`B100`F9d9 // -------------------------`f`b

`B100`F9d9 char letter;`f`b

`B100`F9d9`f`b

`B100`F9d9 // This is a member operation.`f`b

`B100`F9d9 // ---------------------------`f`b

`B100`F9d9 int grade_numeric( const char letter );`f`b

`B100`F9d9`f`b

`B100`F9d9 // This is a class variable.`f`b

`B100`F9d9 // -------------------------`f`b

`B100`F9d9 int numeric;`f`b

`B100`F9d9};`f`b

`B100`F9d9#endif`f`b

A `F33f`_`[constructor`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Constructor_(object-oriented_programming)]`_`f operation is a function with the same name as the class name.`:cite-ref-stroustrup-ch2-49-27-0[`F5bf`_`[26`#cite-note-stroustrup-ch2-49-27]`_`f] It is executed when the calling operation executes the `B100`F9d9new`f`b statement.

A module's other file is the `*`F33f`_`[source file`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Source_code]`_`f`*. Here is a C++ source file for the `*GRADE class`* in a simple school application:

`B100`F9d9// grade.cpp`f`b

`B100`F9d9// ---------`f`b

`B100`F9d9#include "grade.h"`f`b

`B100`F9d9`f`b

`B100`F9d9GRADE::GRADE( const char letter )`f`b

`B100`F9d9{`f`b

`B100`F9d9 // Reference the object using the keyword 'this'.`f`b

`B100`F9d9 // ----------------------------------------------`f`b

`B100`F9d9 this->letter = letter;`f`b

`B100`F9d9`f`b

`B100`F9d9 // This is Temporal Cohesion`f`b

`B100`F9d9 // -------------------------`f`b

`B100`F9d9 this->numeric = grade_numeric( letter );`f`b

`B100`F9d9}`f`b

`B100`F9d9`f`b

`B100`F9d9int GRADE::grade_numeric( const char letter )`f`b

`B100`F9d9{`f`b

`B100`F9d9 if ( ( letter == 'A' || letter == 'a' ) )`f`b

`B100`F9d9 return 4;`f`b

`B100`F9d9 else`f`b

`B100`F9d9 if ( ( letter == 'B' || letter == 'b' ) )`f`b

`B100`F9d9 return 3;`f`b

`B100`F9d9 else`f`b

`B100`F9d9 if ( ( letter == 'C' || letter == 'c' ) )`f`b

`B100`F9d9 return 2;`f`b

`B100`F9d9 else`f`b

`B100`F9d9 if ( ( letter == 'D' || letter == 'd' ) )`f`b

`B100`F9d9 return 1;`f`b

`B100`F9d9 else`f`b

`B100`F9d9 if ( ( letter == 'F' || letter == 'f' ) )`f`b

`B100`F9d9 return 0;`f`b

`B100`F9d9 else`f`b

`B100`F9d9 return -1;`f`b

`B100`F9d9}`f`b

Here is a C++ `*header file`* for the `*PERSON class`* in a simple school application:

`B100`F9d9// person.h`f`b

`B100`F9d9// --------`f`b

`B100`F9d9#ifndef PERSON_H`f`b

`B100`F9d9#define PERSON_H`f`b

`B100`F9d9`f`b

`B100`F9d9class PERSON {`f`b

`B100`F9d9public:`f`b

`B100`F9d9 PERSON ( const char *name );`f`b

`B100`F9d9 const char *name;`f`b

`B100`F9d9};`f`b

`B100`F9d9#endif`f`b

Here is a C++ `*source file`* for the `*PERSON class`* in a simple school application:

`B100`F9d9// person.cpp`f`b

`B100`F9d9// ----------`f`b

`B100`F9d9#include "person.h"`f`b

`B100`F9d9`f`b

`B100`F9d9PERSON::PERSON ( const char *name )`f`b

`B100`F9d9{`f`b

`B100`F9d9 this->name = name;`f`b

`B100`F9d9}`f`b

Here is a C++ `*header file`* for the `*STUDENT class`* in a simple school application:

`B100`F9d9// student.h`f`b

`B100`F9d9// ---------`f`b

`B100`F9d9#ifndef STUDENT_H`f`b

`B100`F9d9#define STUDENT_H`f`b

`B100`F9d9`f`b

`B100`F9d9#include "person.h"`f`b

`B100`F9d9#include "grade.h"`f`b

`B100`F9d9`f`b

`B100`F9d9// A STUDENT is a subset of PERSON.`f`b

`B100`F9d9// --------------------------------`f`b

`B100`F9d9class STUDENT : public PERSON{`f`b

`B100`F9d9public:`f`b

`B100`F9d9 STUDENT ( const char *name );`f`b

`B100`F9d9 ~STUDENT();`f`b

`B100`F9d9 GRADE *grade;`f`b

`B100`F9d9};`f`b

`B100`F9d9#endif`f`b

Here is a C++ `*source file`* for the `*STUDENT class`* in a simple school application:

`B100`F9d9// student.cpp`f`b

`B100`F9d9// -----------`f`b

`B100`F9d9#include "student.h"`f`b

`B100`F9d9#include "person.h"`f`b

`B100`F9d9`f`b

`B100`F9d9STUDENT::STUDENT ( const char *name ):`f`b

`B100`F9d9 // Execute the constructor of the PERSON superclass.`f`b

`B100`F9d9 // -------------------------------------------------`f`b

`B100`F9d9 PERSON( name )`f`b

`B100`F9d9{`f`b

`B100`F9d9 // Nothing else to do.`f`b

`B100`F9d9 // -------------------`f`b

`B100`F9d9}`f`b

`B100`F9d9`f`b

`B100`F9d9STUDENT::~STUDENT()`f`b

`B100`F9d9{`f`b

`B100`F9d9 // deallocate grade's memory`f`b

`B100`F9d9 // to avoid memory leaks.`f`b

`B100`F9d9 // -------------------------------------------------`f`b

`B100`F9d9 delete this->grade;`f`b

`B100`F9d9}`f`b

Here is a driver program for demonstration:

`B100`F9d9// student_dvr.cpp`f`b

`B100`F9d9// ---------------`f`b

`B100`F9d9#include <iostream>`f`b

`B100`F9d9#include "student.h"`f`b

`B100`F9d9`f`b

`B100`F9d9int main( void )`f`b

`B100`F9d9{`f`b

`B100`F9d9 STUDENT *student = new STUDENT( "The Student" );`f`b

`B100`F9d9 student->grade = new GRADE( 'a' );`f`b

`B100`F9d9`f`b

`B100`F9d9 std::cout`f`b

`B100`F9d9 // Notice student inherits PERSON's name`f`b

`B100`F9d9 << student->name`f`b

`B100`F9d9 << ": Numeric grade = "`f`b

`B100`F9d9 << student->grade->numeric`f`b

`B100`F9d9 << "\\n";`f`b

`B100`F9d9`f`b

`B100`F9d9 // deallocate student's memory`f`b

`B100`F9d9 // to avoid memory leaks.`f`b

`B100`F9d9 // -------------------------------------------------`f`b

`B100`F9d9 delete student;`f`b

`B100`F9d9`f`b

`B100`F9d9 return 0;`f`b

`B100`F9d9}`f`b

Here is a `F33f`_`[makefile`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Makefile]`_`f to compile everything:

`B100`F9d9# makefile`f`b

`B100`F9d9# --------`f`b

`B100`F9d9all: student_dvr`f`b

`B100`F9d9`f`b

`B100`F9d9clean:`f`b

`B100`F9d9 rm student_dvr *.o`f`b

`B100`F9d9`f`b

`B100`F9d9student_dvr: student_dvr.cpp grade.o student.o person.o`f`b

`B100`F9d9 c++ student_dvr.cpp grade.o student.o person.o -o student_dvr`f`b

`B100`F9d9`f`b

`B100`F9d9grade.o: grade.cpp grade.h`f`b

`B100`F9d9 c++ -c grade.cpp`f`b

`B100`F9d9`f`b

`B100`F9d9student.o: student.cpp student.h`f`b

`B100`F9d9 c++ -c student.cpp`f`b

`B100`F9d9`f`b

`B100`F9d9person.o: person.cpp person.h`f`b

`B100`F9d9 c++ -c person.cpp`f`b

>>See also

• `F33f`_`[Functional programming`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Functional_programming]`_`f

• `F33f`_`[Reactive programming`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Reactive_programming]`_`f

• `F33f`_`[History of programming languages`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=History_of_programming_languages]`_`f

• `F33f`_`[List of imperative programming languages`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=List_of_programming_languages_by_category]`_`f

>>Notes

`:cite-note-3`!note 1.`! `F0af`_`[↑`#cite-ref-3]`_`f `F33f`_`[Reconfigurable computing`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Reconfigurable_computing]`_`f is a notable exception.

>>References

`:cite-note-1`!1.`! `F0af`_`[↑`#cite-ref-1]`_`f `:citerefjain2022`aJain, Anisha (2022-12-10). "Javascript Promises— Is There a Better Approach?". `*Medium`*. Archived from the original on 2022-12-20. Retrieved 2022-12-20.

`:cite-note-2`!2.`! `F0af`_`[↑`#cite-ref-2]`_`f "Imperative programming: Overview of the oldest programming paradigm". `*IONOS Digitalguide`*. 21 May 2021. Archived from the original on 2022-05-03. Retrieved 2022-05-03.

`:cite-note-0-4`!3.`! `F0af`_`[↑`#cite-ref-0-4-0]`_`f `:citerefbruce-eckel2006`aBruce Eckel (2006). `*Thinking in Java`*. `F33f`_`[Pearson Education`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Pearson_Education]`_`f. p. 24. `F33f`_`[ISBN`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=ISBN_(identifier)]`_`f 978-0-13-187248-6.

`:cite-note-cpl-3rd-ch2-16-5`!4.`! `F0af`_`[↑`#cite-ref-cpl-3rd-ch2-16-5-0]`_`f `:citerefwilson2001`aWilson, Leslie B. (2001). `*Comparative Programming Languages, Third Edition`*. Addison-Wesley. p. 16. `F33f`_`[ISBN`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=ISBN_(identifier)]`_`f 0-201-71012-9.

`:cite-note-cpl-3rd-ch2-24-6`!5.`! `F0af`_`[↑`#cite-ref-cpl-3rd-ch2-24-6-0]`_`f `:citerefwilson2001`aWilson, Leslie B. (2001). `*Comparative Programming Languages, Third Edition`*. Addison-Wesley. p. 24. `F33f`_`[ISBN`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=ISBN_(identifier)]`_`f 0-201-71012-9.

`:cite-note-cpl-3rd-ch2-25-7`!6.`! `F0af`_`[↑`#cite-ref-cpl-3rd-ch2-25-7-0]`_`f `:citerefwilson2001`aWilson, Leslie B. (2001). `*Comparative Programming Languages, Third Edition`*. Addison-Wesley. p. 25. `F33f`_`[ISBN`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=ISBN_(identifier)]`_`f 0-201-71012-9.

`:cite-note-cpl-3rd-ch2-19-8`!7.`! `F0af`_`[↑`#cite-ref-cpl-3rd-ch2-19-8-0]`_`f `:citerefwilson2001`aWilson, Leslie B. (2001). `*Comparative Programming Languages, Third Edition`*. Addison-Wesley. p. 19. `F33f`_`[ISBN`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=ISBN_(identifier)]`_`f 0-201-71012-9.

`:cite-note-cpl-3rd-ch2-30-9`!8.`! `F0af`_`[↑`#cite-ref-cpl-3rd-ch2-30-9-0]`_`f `:citerefwilson2001`aWilson, Leslie B. (2001). `*Comparative Programming Languages, Third Edition`*. Addison-Wesley. p. 30. `F33f`_`[ISBN`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=ISBN_(identifier)]`_`f 0-201-71012-9.

`:cite-note-cpl-3rd-ch2-31-10`!9.`! `F0af`_`[↑`#cite-ref-cpl-3rd-ch2-31-10-0]`_`f `:citerefwilson2001`aWilson, Leslie B. (2001). `*Comparative Programming Languages, Third Edition`*. Addison-Wesley. p. 31. `F33f`_`[ISBN`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=ISBN_(identifier)]`_`f 0-201-71012-9.

`:cite-note-cpl-3rd-ch2-37-11`!10.`! `F0af`_`[↑`#cite-ref-cpl-3rd-ch2-37-11-0]`_`f `:citerefwilson2001`aWilson, Leslie B. (2001). `*Comparative Programming Languages, Third Edition`*. Addison-Wesley. p. 37. `F33f`_`[ISBN`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=ISBN_(identifier)]`_`f 0-201-71012-9.

`:cite-note-geeksforgeeks-12`!11.`! `F0af`_`[↑`#cite-ref-geeksforgeeks-12-0]`_`f "Memory Layout of C Programs". 12 September 2011. Archived from the original on 6 November 2021. Retrieved 25 May 2022.

`:cite-note-cpl-ch1-p31-13`!12.`! `F0af`_`[↑`#cite-ref-cpl-ch1-p31-13-0]`_`f `:citerefkernighanritchie1988`aKernighan, Brian W.; Ritchie, Dennis M. (1988). `*The C Programming Language Second Edition`*. Prentice Hall. p. 31. `F33f`_`[ISBN`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=ISBN_(identifier)]`_`f 0-13-110362-8.

`:cite-note-cpl-3rd-ch6-128-14`!13.`! `F0af`_`[↑`#cite-ref-cpl-3rd-ch6-128-14-0]`_`f `:citerefwilson2001`aWilson, Leslie B. (2001). `*Comparative Programming Languages, Third Edition`*. Addison-Wesley. p. 128. `F33f`_`[ISBN`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=ISBN_(identifier)]`_`f 0-201-71012-9.

`:cite-note-lpi-ch6-p121-15`!14.`! `F0af`_`[↑`#cite-ref-lpi-ch6-p121-15-0]`_`f `:citerefkerrisk2010`aKerrisk, Michael (2010). `*The Linux Programming Interface`*. No Starch Press. p. 121. `F33f`_`[ISBN`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=ISBN_(identifier)]`_`f 978-1-59327-220-3.

`:cite-note-lpi-ch6-p122-16`!15.`! `F0af`_`[↑`#cite-ref-lpi-ch6-p122-16-0]`_`f `:citerefkerrisk2010`aKerrisk, Michael (2010). `*The Linux Programming Interface`*. No Starch Press. p. 122. `F33f`_`[ISBN`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=ISBN_(identifier)]`_`f 978-1-59327-220-3.

`:cite-note-cpl-ch1-p185-17`!16.`! `F0af`_`[↑`#cite-ref-cpl-ch1-p185-17-0]`_`f `:citerefkernighanritchie1988`aKernighan, Brian W.; Ritchie, Dennis M. (1988). `*The C Programming Language Second Edition`*. Prentice Hall. p. 185. `F33f`_`[ISBN`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=ISBN_(identifier)]`_`f 0-13-110362-8.

`:cite-note-cpl-ch8-p187-18`!17.`! `F0af`_`[↑`#cite-ref-cpl-ch8-p187-18-0]`_`f `:citerefkernighanritchie1988`aKernighan, Brian W.; Ritchie, Dennis M. (1988). `*The C Programming Language Second Edition`*. Prentice Hall. p. 187. `F33f`_`[ISBN`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=ISBN_(identifier)]`_`f 0-13-110362-8.

`:cite-note-cpl-3rd-ch2-38-19`!18.`! `F0af`_`[↑`#cite-ref-cpl-3rd-ch2-38-19-0]`_`f `:citerefwilson2001`aWilson, Leslie B. (2001). `*Comparative Programming Languages, Third Edition`*. Addison-Wesley. p. 38. `F33f`_`[ISBN`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=ISBN_(identifier)]`_`f 0-201-71012-9.

`:cite-note-stroustrup-ch3-65-20`!19.`! `F0af`_`[↑`#cite-ref-stroustrup-ch3-65-20-0]`_`f `:citerefstroustrup2013`aStroustrup, Bjarne (2013). `*The C++ Programming Language, Fourth Edition`*. Addison-Wesley. p. 65. `F33f`_`[ISBN`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=ISBN_(identifier)]`_`f 978-0-321-56384-2.

`:cite-note-cpl-3rd-ch8-193-21`!20.`! `F0af`_`[↑`#cite-ref-cpl-3rd-ch8-193-21-0]`_`f `:citerefwilson2001`aWilson, Leslie B. (2001). `*Comparative Programming Languages, Third Edition`*. Addison-Wesley. p. 193. `F33f`_`[ISBN`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=ISBN_(identifier)]`_`f 0-201-71012-9.

`:cite-note-cpl-3rd-ch2-39-22`!21.`! `F0af`_`[↑`#cite-ref-cpl-3rd-ch2-39-22-0]`_`f `:citerefwilson2001`aWilson, Leslie B. (2001). `*Comparative Programming Languages, Third Edition`*. Addison-Wesley. p. 39. `F33f`_`[ISBN`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=ISBN_(identifier)]`_`f 0-201-71012-9.

`:cite-note-cpl-3rd-ch2-35-23`!22.`! `F0af`_`[↑`#cite-ref-cpl-3rd-ch2-35-23-0]`_`f `:citerefwilson2001`aWilson, Leslie B. (2001). `*Comparative Programming Languages, Third Edition`*. Addison-Wesley. p. 35. `F33f`_`[ISBN`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=ISBN_(identifier)]`_`f 0-201-71012-9.

`:cite-note-cpl-3rd-ch8-192-24`!23.`! `F0af`_`[↑`#cite-ref-cpl-3rd-ch8-192-24-0]`_`f `:citerefwilson2001`aWilson, Leslie B. (2001). `*Comparative Programming Languages, Third Edition`*. Addison-Wesley. p. 192. `F33f`_`[ISBN`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=ISBN_(identifier)]`_`f 0-201-71012-9.

`:cite-note-stroustrup-notes-22-25`!24.`! `F0af`_`[↑`#cite-ref-stroustrup-notes-22-25-0]`_`f `:citerefstroustrup2013`aStroustrup, Bjarne (2013). `*The C++ Programming Language, Fourth Edition`*. Addison-Wesley. p. 22. `F33f`_`[ISBN`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=ISBN_(identifier)]`_`f 978-0-321-56384-2.

`:cite-note-stroustrup-notes-21-26`!25.`! `F0af`_`[↑`#cite-ref-stroustrup-notes-21-26-0]`_`f `:citerefstroustrup2013`aStroustrup, Bjarne (2013). `*The C++ Programming Language, Fourth Edition`*. Addison-Wesley. p. 21. `F33f`_`[ISBN`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=ISBN_(identifier)]`_`f 978-0-321-56384-2.

`:cite-note-stroustrup-ch2-49-27`!26.`! `F0af`_`[↑`#cite-ref-stroustrup-ch2-49-27-0]`_`f `:citerefstroustrup2013`aStroustrup, Bjarne (2013). `*The C++ Programming Language, Fourth Edition`*. Addison-Wesley. p. 49. `F33f`_`[ISBN`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=ISBN_(identifier)]`_`f 978-0-321-56384-2.

• Pratt, Terrence W. and `F33f`_`[Marvin V. Zelkowitz`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Marvin_Victor_Zelkowitz]`_`f. `*Programming Languages: Design and Implementation`*, 3rd ed. Englewood Cliffs, N.J.: Prentice Hall, 1996.

• Sebesta, Robert W. `*Concepts of Programming Languages`*, 3rd ed. Reading, Mass.: Addison-Wesley Publishing Company, 1996.

`*Originally based on the article 'Imperative programming' by Stan Seibert, from `F33f`_`[Nupedia`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=Nupedia]`_`f, licensed under the `F33f`_`[GNU Free Documentation License`:/page/wikibook/entry.mu`zim=wikipedia_en_all_nopic_2025-08.zim|entry_path=GNU_Free_Documentation_License]`_`f.`*

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