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86-466: AP Computer Science was taught using Pascal for the 1984–1998 exams, C++ for 1999–2003, and Java since 2004. There are two AP computer science courses currently offered. Computer Science Principles is considered to be a more "big picture" course than the programming-intensive Computer Science A. AP Computer Science A is a programming-based course, equivalent to a first-semester–level college course. AP CSA emphasizes object-oriented programming and

172-627: A distributed operating system . IP Pascal is an implementation of the Pascal programming language using Micropolis DOS, but was moved rapidly to CP/M-80 running on the Z80. It was moved to the 80386 machine types in 1994, and exists today as Windows XP and Linux implementations. In 2008, the system was brought up to a new level and the resulting language termed "Pascaline" (after Pascal's calculator ). It includes objects, namespace controls, dynamic arrays , and many other extensions, and generally features

258-488: A "byte machine", again, because it would be a better fit for byte oriented microprocessors. UCSD Pascal formed the basis of many systems, including Apple Pascal. Borland Pascal was not based on the UCSD codebase, but arrived during the popular period of UCSD and matched many of its features. This started the line that ended with Delphi Pascal and the compatible Open Source compiler FPC/Lazarus. The ISO standard for Pascal, ISO 7185,

344-452: A certain platform or with a particular compiler, due, for example, to the use of non-standard libraries, such as GUI libraries, or to a reliance on compiler- or platform-specific attributes such as the exact size of data types and byte endianness . In cases where code must be compilable by either standard-conforming or K&R C-based compilers, the __STDC__ macro can be used to split the code into Standard and K&R sections to prevent

430-486: A full-year college course. Due to low numbers of students taking the exam, AP Computer Science AB was discontinued following the May 2009 exam administration. Pascal (programming language) Pascal is an imperative and procedural programming language , designed by Niklaus Wirth as a small, efficient language intended to encourage good programming practices using structured programming and data structuring . It

516-543: A much more complex language, ALGOL 68 . The complexity of this language led to considerable difficulty producing high-performance compilers, and it was not widely used in the industry. This left an opening for newer languages. Pascal was influenced by the ALGOL W efforts, with the explicit goals of teaching programming in a structured fashion and for the development of system software. A generation of students used Pascal as an introductory language in undergraduate courses. One of

602-628: A return statement and expressions as names of types. TMT Pascal was the first Borland -compatible compiler for 32-bit MS-DOS compatible protected mode , OS/2 , and Win32 . It extends the language with function and operator overloading . The universities of Wisconsin–Madison , Zürich , Karlsruhe , and Wuppertal developed the Pascal-SC and Pascal-XSC ( Extensions for Scientific Computation ) compilers, aimed at programming numerical computations. Development for Pascal-SC started in 1978 supporting ISO 7185 Pascal level 0, but level 2 support

688-590: A semicolon; as a side effect of the evaluation, functions may be called and variables assigned new values. To modify the normal sequential execution of statements, C provides several control-flow statements identified by reserved keywords. Structured programming is supported by if ... [ else ] conditional execution and by do ... while , while , and for iterative execution (looping). The for statement has separate initialization, testing, and reinitialization expressions, any or all of which can be omitted. break and continue can be used within

774-420: A single statement or a begin - end statements block. Pascal also has data structuring constructs not included in the original ALGOL 60 types , like records , variants, pointers , enumerations , and sets and procedure pointers. Such constructs were in part inherited or inspired from Simula 67, ALGOL 68 , Niklaus Wirth 's own ALGOL W and suggestions by C. A. R. Hoare . Pascal programs start with

860-494: A subset of the Pascal language. Pascal-P5, created outside the Zürich group, accepts the full Pascal language and includes ISO 7185 compatibility. Pascal-P6 is a follow on to Pascal-P5 that along with other features, aims to be a compiler for specific CPUs, including AMD64. UCSD Pascal branched off Pascal-P2, where Kenneth Bowles used it to create the interpretive UCSD p-System. It was one of three operating systems available at

946-473: A very simple "Hello, World!" program : A Type Declaration in Pascal is used to define a range of values which a variable of that type is capable of storing. It also defines a set of operations that are permissible to be performed on variables of that type. The predefined types are: The range of values allowed for the basic types (except Boolean) is implementation defined. Functions are provided for some data conversions. For conversion of real to integer ,

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1032-423: A warning message if a local function was called with the wrong number of arguments, or if different calls to an external function used different numbers or types of arguments. Separate tools such as Unix's lint utility were developed that (among other things) could check for consistency of function use across multiple source files. In the years following the publication of K&R C, several features were added to

1118-589: A wide variety of mainframe computers , minicomputers , and microcomputers , including the IBM PC , as its popularity began to increase significantly. In 1983 the American National Standards Institute (ANSI) formed a committee, X3J11, to establish a standard specification of C. X3J11 based the C standard on the Unix implementation; however, the non-portable portion of the Unix C library was handed off to

1204-494: Is an imperative , procedural language in the ALGOL tradition. It has a static type system . In C, all executable code is contained within subroutines (also called "functions", though not in the sense of functional programming ). Function parameters are passed by value, although arrays are passed as pointers , i.e. the address of the first item in the array. Pass-by-reference is simulated in C by explicitly passing pointers to

1290-505: Is an accepted version of this page C ( pronounced / ˈ s iː / – like the letter c ) is a general-purpose programming language . It was created in the 1970s by Dennis Ritchie and remains very widely used and influential. By design, C's features cleanly reflect the capabilities of the targeted CPUs. It has found lasting use in operating systems code (especially in kernels ), device drivers , and protocol stacks , but its use in application software has been decreasing. C

1376-451: Is an informal name for the current major C language standard revision. It was informally known as "C2X" through most of its development. C23 was published in October 2024 as ISO/IEC 9899:2024. The standard macro __STDC_VERSION__ is defined as 202311L to indicate that C23 support is available. C2Y is an informal name for the next major C language standard revision, after C23 (C2X), that

1462-456: Is commonly used on computer architectures that range from the largest supercomputers to the smallest microcontrollers and embedded systems . A successor to the programming language B , C was originally developed at Bell Labs by Ritchie between 1972 and 1973 to construct utilities running on Unix . It was applied to re-implementing the kernel of the Unix operating system. During the 1980s, C gradually gained popularity. It has become one of

1548-497: Is defined as 201112L to indicate that C11 support is available. C17 is an informal name for ISO/IEC 9899:2018, a standard for the C programming language published in June 2018. It introduces no new language features, only technical corrections, and clarifications to defects in C11. The standard macro __STDC_VERSION__ is defined as 201710L to indicate that C17 support is available. C23

1634-516: Is for the most part backward compatible with C90, but is stricter in some ways; in particular, a declaration that lacks a type specifier no longer has int implicitly assumed. A standard macro __STDC_VERSION__ is defined with value 199901L to indicate that C99 support is available. GCC , Solaris Studio , and other C compilers now support many or all of the new features of C99. The C compiler in Microsoft Visual C++ , however, implements

1720-464: Is hoped to be released later in the 2020s decade, hence the '2' in "C2Y". An early working draft of C2Y was released in February 2024 as N3220 by the working group ISO/IEC JTC1/SC22 /WG14. Historically, embedded C programming requires non-standard extensions to the C language to support exotic features such as fixed-point arithmetic , multiple distinct memory banks , and basic I/O operations. In 2008,

1806-818: Is named after French mathematician, philosopher and physicist Blaise Pascal . Pascal was developed on the pattern of the ALGOL 60 language. Wirth was involved in the process to improve the language as part of the ALGOL X efforts and proposed a version named ALGOL W . This was not accepted, and the ALGOL X process bogged down. In 1968, Wirth decided to abandon the ALGOL X process and further improve ALGOL W, releasing this as Pascal in 1970. On top of ALGOL's scalars and arrays , Pascal enables defining complex datatypes and building dynamic and recursive data structures such as lists , trees and graphs . Pascal has strong typing on all objects, which means that one type of data cannot be converted to or interpreted as another without explicit conversions. Unlike C (and most languages in

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1892-622: Is now also referred to as C78 . The second edition of the book covers the later ANSI C standard, described below. K&R introduced several language features: Even after the publication of the 1989 ANSI standard, for many years K&R C was still considered the " lowest common denominator " to which C programmers restricted themselves when maximum portability was desired, since many older compilers were still in use, and because carefully written K&R C code can be legal Standard C as well. In early versions of C, only functions that return types other than int must be declared if used before

1978-420: Is sometimes called C90. Therefore, the terms "C89" and "C90" refer to the same programming language. ANSI, like other national standards bodies, no longer develops the C standard independently, but defers to the international C standard, maintained by the working group ISO/IEC JTC1/SC22 /WG14. National adoption of an update to the international standard typically occurs within a year of ISO publication. One of

2064-541: Is still used for developing Windows applications, and can cross-compile code to other systems. Free Pascal is an open source, cross-platform alternative with its own graphical IDE called Lazarus . The first Pascal compiler was designed in Zürich for the CDC 6000 series mainframe computer family. Niklaus Wirth reports that a first attempt to implement it in FORTRAN 66 in 1969

2150-478: Is taught using the programming language of Java . The course has an emphasis on problem-solving using data structures and algorithms . AP Computer Science Principles is an introductory college-level course in computer science with an emphasis on computational thinking and the impacts of computing. The course has no designated programming language, and teaches algorithms and programming , complementing Computer Science A. AP Computer Science AB included all

2236-652: Is usually capable of recompiling itself when new features are added to the language, or when the compiler is to be ported to a new environment. The GNU Pascal compiler is one notable exception, being written in C. The first successful port of the CDC Pascal compiler to another mainframe was completed by Welsh and Quinn at the Queen's University of Belfast (QUB) in 1972. The target was the International Computers Limited (ICL) 1900 series . This compiler, in turn,

2322-457: The program keyword with a list of external file descriptors as parameters (not required in Turbo Pascal etc.); then follows the main block bracketed by the begin and end keywords. Semicolons separate statements , and the full stop (i.e., a period) ends the whole program (or unit ). Letter case is ignored in Pascal source. Here is an example of the source code in use for

2408-485: The C-family ), Pascal allows nested procedure definitions to any level of depth, and also allows most kinds of definitions and declarations inside subroutines (procedures and functions). A program is thus syntactically similar to a single procedure or function. This is similar to the block structure of ALGOL 60, but restricted from arbitrary block statements to just procedures and functions. Pascal became very successful in

2494-451: The Euler programming language . Euler was based on ALGOL's syntax and many concepts but was not a derivative. Its primary goal was to add dynamic lists and types, allowing it to be used in roles similar to Lisp . The language was published in 1965. By this time, a number of problems in ALGOL had been identified, notably the lack of a standardized string system. The group tasked with maintaining

2580-578: The IEEE working group 1003 to become the basis for the 1988 POSIX standard. In 1989, the C standard was ratified as ANSI X3.159-1989 "Programming Language C". This version of the language is often referred to as ANSI C , Standard C, or sometimes C89. In 1990 the ANSI C standard (with formatting changes) was adopted by the International Organization for Standardization (ISO) as ISO/IEC 9899:1990, which

2666-574: The International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). C is an imperative procedural language, supporting structured programming , lexical variable scope , and recursion , with a static type system . It was designed to be compiled to provide low-level access to memory and language constructs that map efficiently to machine instructions , all with minimal runtime support . Despite its low-level capabilities,

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2752-404: The 1970s, notably on the burgeoning minicomputer market. Compilers were also available for many microcomputers as the field emerged in the late 1970s. It was widely used as a teaching language in university -level programming courses in the 1980s, and also used in production settings for writing commercial software during the same period. It was displaced by the C programming language during

2838-483: The C Standards Committee published a technical report extending the C language to address these issues by providing a common standard for all implementations to adhere to. It includes a number of features not available in normal C, such as fixed-point arithmetic, named address spaces, and basic I/O hardware addressing. C has a formal grammar specified by the C standard. Line endings are generally not significant in C; however, line boundaries do have significance during

2924-536: The C-based application programming interface (API) of Microsoft Windows directly. These extensions included null-terminated strings , pointer arithmetic , function pointers , an address-of operator, and unsafe typecasts . Turbo Pascal and other derivatives with unit or module structures are modular programming languages. However, it does not provide a nested module concept or qualified import and export of specific symbols. Super Pascal adds non-numeric labels,

3010-591: The C89 standard and those parts of C99 that are required for compatibility with C++11 . In addition, the C99 standard requires support for identifiers using Unicode in the form of escaped characters (e.g. \u0040 or \U0001f431 ) and suggests support for raw Unicode names. Work began in 2007 on another revision of the C standard, informally called "C1X" until its official publication of ISO/IEC 9899:2011 on December 8, 2011. The C standards committee adopted guidelines to limit

3096-566: The Lisa Pascal and Mac Pascal compilers. In the 1980s, Anders Hejlsberg wrote the Blue Label Pascal compiler for the Nascom -2. A reimplementation of this compiler for the IBM PC was marketed under the names Compas Pascal and PolyPascal before it was acquired by Borland and renamed Turbo Pascal . Turbo Pascal became hugely popular, thanks to an aggressive pricing strategy, having one of

3182-623: The Macintosh, a further version was created and named Object Pascal . This was introduced on the Mac in 1985 as part of the MacApp application framework , and became Apple's main development language into the early 1990s. The Object Pascal extensions were added to Turbo Pascal with the release of version 5.5 in 1989. Over the years, Object Pascal became the basis of the Delphi system for Microsoft Windows , which

3268-602: The Pascal source code . The typesetting system TeX by Donald Knuth was written in WEB , the original literate programming system, based on DEC PDP-10 Pascal. Successful commercial applications like Adobe Photoshop were written in Macintosh Programmer's Workshop Pascal, while applications like Total Commander , Skype and Macromedia Captivate were written in Delphi ( Object Pascal ). Apollo Computer used Pascal as

3354-519: The Pascal concepts led to the languages Modula-2 and Oberon , both developed by Wirth. Much of the history of computer language design during the 1960s can be traced to the ALGOL 60 language. ALGOL was developed during the 1950s with the explicit goal of being able to clearly describe algorithms . It included a number of features for structured programming that remain common in languages to this day. Shortly after its introduction, in 1962 Wirth began working on his dissertation with Helmut Weber on

3440-895: The Pascal-P4 compiler, which created native binary object files , was released for the IBM System/370 mainframe computer by the Australian Atomic Energy Commission ; it was named the AAEC Pascal 8000 Compiler after the abbreviation of the name of the commission. Apple Computer created its own Lisa Pascal for the Lisa Workshop in 1982, and ported the compiler to the Apple Macintosh and MPW in 1985. In 1985 Larry Tesler , in consultation with Niklaus Wirth, defined Object Pascal and these extensions were incorporated in both

3526-438: The adoption of new features that had not been tested by existing implementations. The C11 standard adds numerous new features to C and the library, including type generic macros, anonymous structures, improved Unicode support, atomic operations, multi-threading, and bounds-checked functions. It also makes some portions of the existing C99 library optional, and improves compatibility with C++. The standard macro __STDC_VERSION__

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3612-428: The aims of the C standardization process was to produce a superset of K&R C, incorporating many of the subsequently introduced unofficial features. The standards committee also included several additional features such as function prototypes (borrowed from C++), void pointers, support for international character sets and locales , and preprocessor enhancements. Although the syntax for parameter declarations

3698-416: The basis for several implementations of C on new platforms. In 1978 Brian Kernighan and Dennis Ritchie published the first edition of The C Programming Language . Known as K&R from the initials of its authors, the book served for many years as an informal specification of the language. The version of C that it describes is commonly referred to as " K&R C ". As this was released in 1978, it

3784-478: The built-in set to cover most machine data types like 16-bit integers. The packed keyword tells the compiler to use the most efficient method of storage for the structured data types: sets, arrays and records, rather than using one word for each element. Packing may slow access on machines that do not offer easy access to parts of a word. Subranges of any ordinal data type (any simple type except real) can also be made: C (programming language) This

3870-514: The early history on Pascal can be found in the Pascal User's Group newsletters at: Pascal Users Group Newsletters . During work on the Lisa, Larry Tesler began corresponding with Wirth on the idea of adding object-oriented extensions to the language, to make Pascal a Multi-paradigm programming language . This led initially to Clascal , introduced in 1983. As the Lisa program faded and was replaced by

3956-656: The early successes for the language was the introduction of UCSD Pascal , a version that ran on a custom operating system that could be ported to different platforms. A key platform was the Apple II , where it saw widespread use as Apple Pascal . This led to Pascal becoming the primary high-level language used for development in the Apple Lisa , and later, the Macintosh . Parts of the original Macintosh operating system were hand-translated into Motorola 68000 assembly language from

4042-643: The features of the more-powerful PDP-11. A significant addition was a character data type. He called this New B (NB). Thompson started to use NB to write the Unix kernel, and his requirements shaped the direction of the language development. Through to 1972, richer types were added to the NB language: NB had arrays of int and char . Pointers, the ability to generate pointers to other types, arrays of all types, and types to be returned from functions were all also added. Arrays within expressions became pointers. A new compiler

4128-515: The first 16-bit implementation. A completely new compiler was completed by Welsh et al. at QUB in 1977. It offered a source-language diagnostic feature (incorporating profiling, tracing and type-aware formatted postmortem dumps) that was implemented by Findlay and Watt at Glasgow University. This implementation was ported in 1980 to the ICL 2900 series by a team based at Southampton University and Glasgow University. The Standard Pascal Model Implementation

4214-492: The first full-screen IDEs, and very fast turnaround time (just seconds to compile, link, and run). It was written and highly optimized entirely in assembly language , making it smaller and faster than much of the competition. In 1986, Anders ported Turbo Pascal to the Macintosh and incorporated Apple's Object Pascal extensions into Turbo Pascal. These extensions were then added back into the PC version of Turbo Pascal for version 5.5. At

4300-420: The following functions are available: round (which rounds to integer using banker's rounding ) and trunc (rounds towards zero). The programmer has the freedom to define other commonly used data types (e.g. byte, string, etc.) in terms of the predefined types using Pascal's type declaration facility, for example Often-used types like byte and string are already defined in many implementations. Normally

4386-473: The function definition; functions used without prior declaration were presumed to return type int . For example: The int type specifiers which are commented out could be omitted in K&;R C, but are required in later standards. Since K&R function declarations did not include any information about function arguments, function parameter type checks were not performed, although some compilers would issue

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4472-407: The language had begun the ALGOL X process to identify improvements, calling for submissions. Wirth and Tony Hoare submitted a conservative set of modifications to add strings and clean up some of the syntax. These were considered too minor to be worth using as the new standard ALGOL, so Wirth wrote a compiler for the language, which became named ALGOL W . The ALGOL X efforts would go on to choose

4558-471: The language rapidly, a compiler porting kit was created in Zürich that included a compiler that generated so called p-code for a virtual stack machine, i.e., code that lends itself to reasonably efficient interpretation, along with an interpreter for that code – the Pascal-P system. The P-system compilers were named Pascal-P1, Pascal-P2, Pascal-P3, and Pascal-P4. Pascal-P1 was the first version, and Pascal-P4

4644-448: The language was designed to encourage cross-platform programming. A standards -compliant C program written with portability in mind can be compiled for a wide variety of computer platforms and operating systems with few changes to its source code. Since 2000, C has consistently ranked among the top four languages in the TIOBE index , a measure of the popularity of programming languages. C

4730-438: The language, supported by compilers from AT&T (in particular PCC ) and some other vendors. These included: The large number of extensions and lack of agreement on a standard library , together with the language popularity and the fact that not even the Unix compilers precisely implemented the K&R specification, led to the necessity of standardization. During the late 1970s and 1980s, versions of C were implemented for

4816-463: The late 1980s and early 1990s as UNIX -based systems became popular, and especially with the release of C++ . A derivative named Object Pascal designed for object-oriented programming was developed in 1985. This was used by Apple Computer (for the Lisa and Macintosh machines) and Borland in the late 1980s and later developed into Delphi on the Microsoft Windows platform. Extensions to

4902-485: The launch of the original IBM Personal Computer . UCSD Pascal used an intermediate code based on byte values, and thus was one of the earliest bytecode compilers . Apple Pascal was released in 1979 for the Apple II and Apple III computer systems. It was an implementation of, or largely based on, UCSD Pascal. Pascal-P1 through Pascal-P4 were not, but rather based on the CDC 6600 60-bit word length. A compiler based on

4988-413: The loop. Break is used to leave the innermost enclosing loop statement and continue is used to skip to its reinitialisation. There is also a non-structured goto statement which branches directly to the designated label within the function. switch selects a case to be executed based on the value of an integer expression. Different from many other languages, control-flow will fall through to

5074-425: The most widely used programming languages, with C compilers available for practically all modern computer architectures and operating systems. The book The C Programming Language , co-authored by the original language designer, served for many years as the de facto standard for the language. C has been standardized since 1989 by the American National Standards Institute (ANSI) and, subsequently, jointly by

5160-411: The next case unless terminated by a break . Expressions can use a variety of built-in operators and may contain function calls. The order in which arguments to functions and operands to most operators are evaluated is unspecified. The evaluations may even be interleaved. However, all side effects (including storage to variables) will occur before the next " sequence point "; sequence points include

5246-419: The operating system to a PDP-11 . The original PDP-11 version of Unix was also developed in assembly language. Thompson wanted a programming language for developing utilities for the new platform. He first tried writing a Fortran compiler, but he soon gave up the idea and instead created a cut-down version of the recently developed systems programming language called BCPL . The official description of BCPL

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5332-652: The preprocessing phase. Comments may appear either between the delimiters /* and */ , or (since C99) following // until the end of the line. Comments delimited by /* and */ do not nest, and these sequences of characters are not interpreted as comment delimiters if they appear inside string or character literals. C source files contain declarations and function definitions. Function definitions, in turn, contain declarations and statements . Declarations either define new types using keywords such as struct , union , and enum , or assign types to and perhaps reserve storage for new variables, usually by writing

5418-408: The recognizable expression and statement syntax of C with underlying type systems, data models, and semantics that can be radically different. The origin of C is closely tied to the development of the Unix operating system, originally implemented in assembly language on a PDP-7 by Dennis Ritchie and Ken Thompson , incorporating several ideas from colleagues. Eventually, they decided to port

5504-423: The same functionality and type protection as C# . It is the only such implementation that is also compatible with the original Pascal implementation, which is standardized as ISO 7185. Pascal, in its original form, is a purely procedural language and includes the traditional array of ALGOL -like control structures with reserved words such as if , then , else , while , for , and case , ranging on

5590-543: The same time Microsoft also implemented the Object Pascal compiler. Turbo Pascal 5.5 had a large influence on the Pascal community, which began concentrating mainly on the IBM PC in the late 1980s. Many PC hobbyists in search of a structured replacement for BASIC used this product. It also began to be adopted by professional developers. Around the same time a number of concepts were imported from C to let Pascal programmers use

5676-399: The system will use a word to store the data. For instance, the byte type may be stored in a machine integer - 32 bits perhaps - rather than an 8-bit value. Pascal does not contain language elements that allow the basic storage types to be defined more granularly. This capability was included in a number of Pascal extensions and follow-on languages, while others, like Modula-2 , expanded

5762-495: The systems programming language for its operating systems beginning in 1980. Variants of Pascal have also been used for everything from research projects to PC games and embedded systems . Newer Pascal compilers exist which are widely used. Wirth's example compiler meant to propagate the language, the Pascal-P system, used a subset of the language designed to be the minimal subset of the language that could compile itself. The idea

5848-415: The thing being referenced. C program source text is free-form code. Semicolons terminate statements , while curly braces are used to group statements into blocks . The C language also exhibits the following characteristics: While C does not include certain features found in other languages (such as object orientation and garbage collection ), these can be implemented or emulated, often through

5934-541: The topics of AP Computer Science A, as well as a more formal and a more in-depth study of algorithms , data structures , and data abstraction . For example, binary trees were studied in AP Computer Science AB but not in AP Computer Science A. The use of recursive data structures and dynamically allocated structures were fundamental to AP Computer Science AB. AP Computer Science AB was equivalent to

6020-468: The type followed by the variable name. Keywords such as char and int specify built-in types. Sections of code are enclosed in braces ( { and } , sometimes called "curly brackets") to limit the scope of declarations and to act as a single statement for control structures. As an imperative language, C uses statements to specify actions. The most common statement is an expression statement , consisting of an expression to be evaluated, followed by

6106-472: The urging of Alan Snyder and also in recognition of the usefulness of the file-inclusion mechanisms available in BCPL and PL/I . Its original version provided only included files and simple string replacements: #include and #define of parameterless macros. Soon after that, it was extended, mostly by Mike Lesk and then by John Reiser, to incorporate macros with arguments and conditional compilation . Unix

6192-703: The use of external libraries (e.g., the GLib Object System or the Boehm garbage collector ). Many later languages have borrowed directly or indirectly from C, including C++ , C# , Unix's C shell , D , Go , Java , JavaScript (including transpilers ), Julia , Limbo , LPC , Objective-C , Perl , PHP , Python , Ruby , Rust , Swift , Verilog and SystemVerilog (hardware description languages). These languages have drawn many of their control structures and other basic features from C. Most of them also express highly similar syntax to C, and they tend to combine

6278-531: The use on a K&R C-based compiler of features available only in Standard C. After the ANSI/ISO standardization process, the C language specification remained relatively static for several years. In 1995, Normative Amendment 1 to the 1990 C standard (ISO/IEC 9899/AMD1:1995, known informally as C95) was published, to correct some details and to add more extensive support for international character sets. The C standard

6364-575: Was added at a later stage. Pascal-SC originally targeted the Z80 processor, but was later rewritten for DOS ( x86 ) and 68000 . Pascal-XSC has at various times been ported to Unix (Linux, SunOS , HP-UX , AIX ) and Microsoft/IBM (DOS with EMX , OS/2, Windows ) operating systems. It operates by generating intermediate C source code which is then compiled to a native executable. Some of the Pascal-SC language extensions have been adopted by GNU Pascal . Pascal Sol

6450-627: Was also based on this compiler, having been adapted, by Welsh and Hay at Manchester University in 1984, to check rigorously for conformity to the BSI 6192/ISO 7185 Standard and to generate code for a portable abstract machine. The first Pascal compiler written in North America was constructed at the University of Illinois under Donald B. Gillies for the PDP-11 and generated native machine code. To propagate

6536-510: Was augmented to include the style used in C++, the K&R interface continued to be permitted, for compatibility with existing source code. C89 is supported by current C compilers, and most modern C code is based on it. Any program written only in Standard C and without any hardware-dependent assumptions will run correctly on any platform with a conforming C implementation, within its resource limits. Without such precautions, programs may compile only on

6622-502: Was designed around 1983 by a French team to implement a Unix-like system named Sol. It was standard Pascal level-1 (with parameterized array bounds) but the definition allowed alternative keywords and predefined identifiers in French and the language included a few extensions to ease system programming (e.g. an equivalent to lseek). The Sol team later on moved to the ChorusOS project to design

6708-706: Was further revised in the late 1990s, leading to the publication of ISO/IEC 9899:1999 in 1999, which is commonly referred to as " C99 ". It has since been amended three times by Technical Corrigenda. C99 introduced several new features, including inline functions , several new data types (including long long int and a complex type to represent complex numbers ), variable-length arrays and flexible array members , improved support for IEEE 754 floating point, support for variadic macros (macros of variable arity ), and support for one-line comments beginning with // , as in BCPL or C++. Many of these had already been implemented as extensions in several C compilers. C99

6794-511: Was not available at the time, and Thompson modified the syntax to be less 'wordy' and similar to a simplified ALGOL known as SMALGOL. He called the result B , describing it as "BCPL semantics with a lot of SMALGOL syntax". Like BCPL, B had a bootstrapping compiler to facilitate porting to new machines. Ultimately, few utilities were written in B because it was too slow and could not take advantage of PDP-11 features such as byte addressability. In 1971 Ritchie started to improve B, to use

6880-612: Was one of the first operating system kernels implemented in a language other than assembly . Earlier instances include the Multics system (which was written in PL/I ) and Master Control Program (MCP) for the Burroughs B5000 (which was written in ALGOL ) in 1961. In around 1977, Ritchie and Stephen C. Johnson made further changes to the language to facilitate portability of the Unix operating system. Johnson's Portable C Compiler served as

6966-512: Was published in 1983 and was widely implemented and used on mainframes, minicomputers and IBM-PCs and compatibles from 16 bits to 32 bits. The two dialects of Pascal most in use towards the end of the 20th century and up until today are the ISO 7185 standard version and the Delphi/Turbo Pascal versions (of which the two Borland versions are mostly compatible with each other). The source for much of

7052-470: Was that this could allow bootstrapping the compiler, which would then be extended to full Pascal language status. This was done with several compilers, but one notable exception was UCSD Pascal, which was based on Pascal-P2. It kept the subset status of the language based on the idea that this would run better on the new (then) microprocessors with limited memory. UCSD also converted the Pascal-P2 interpreter into

7138-544: Was the last to come from Zürich. The version termed Pascal-P1 was coined after the fact for the many different sources for Pascal-P that existed. The compiler was redesigned to enhance portability , and issued as Pascal-P2. This code was later enhanced to become Pascal-P3, with an intermediate code backward compatible with Pascal-P2, and Pascal-P4, which was not backward compatible. The Pascal-P4 compiler–interpreter can still be run and compiled on systems compatible with original Pascal (as can Pascal-P2). However, it only accepts

7224-587: Was the parent of the Pascal compiler for the Information Computer Systems (ICS) Multum minicomputer. The Multum port was developed – with a view to using Pascal as a systems programming language – by Findlay, Cupples, Cavouras and Davis, working at the Department of Computing Science in Glasgow University . It is thought that Multum Pascal, which was completed in the summer of 1973, may have been

7310-408: Was unsuccessful due to FORTRAN 66's inadequacy to express complex data structures. The second attempt was implemented in a C-like language (Scallop by Max Engeli) and then translated by hand (by R. Schild) to Pascal itself for boot-strapping. It was operational by mid-1970. Many Pascal compilers since have been similarly self-hosting , that is, the compiler is itself written in Pascal, and the compiler

7396-520: Was written, and the language was renamed C. The C compiler and some utilities made with it were included in Version 2 Unix , which is also known as Research Unix . At Version 4 Unix , released in November 1973, the Unix kernel was extensively re-implemented in C. By this time, the C language had acquired some powerful features such as struct types. The preprocessor was introduced around 1973 at

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