The history and status of C language
The C language was born in Bell Laboratories in the United States . It was developed by Dennis MacAlistair Ritchie based on the B language designed by Kenneth Lane Thompson . After its main design was completed, Thompson and Rich used it to completely rewrite UNIX, and with the development of UNIX, the c language has also been continuously improved. In order to facilitate the comprehensive promotion of C language, many experts, scholars and hardware manufacturers jointly formed the C language standard committee, and in 1989, the first complete C standard was born, referred to as "C89", also known as " ANSI C " . , as of 2020, the latest C language standard is "C18" released in June 2018. The reason why the C language is named C is because the C language is derived from the B language invented by Ken Thompson , and the B language is derived from the BCPL language.
In 1967, Martin Richards of Cambridge University simplified the CPL language , resulting in the BCPL (Basic Combined Programming Language) language.
In the 1960s, Kenneth Lane Thompson (Kenneth Lane Thompson), a researcher at AT&T Bell Laboratories in the United States, had nothing to do, his hands itched, and he wanted to play a video game he made up to simulate sailing in the solar system ——Space Travel. Behind his back, he found an idle small computer—— PDP-7 . But the computer didn't have an operating system, and games had to use some features of the operating system, so he set out to develop an operating system for the PDP-7. Later, this operating system was named - UNICS (Uniplexed Information and Computing Service).
In 1969, Ken Thompson of Bell Laboratories in the United States , based on the BCPL language, designed a very simple and very close to the hardware B language (taking the initials of BCPL), and wrote the first version of the UNIX operating system (called UNICS) in the B language. .
In 1971, Dennis Rich, who also loves Space Travel, joined Thompson's development project in order to play the game earlier, and jointly developed UNIX. His main job is to transform the B language to make it more mature. [6]
In 1972, Dennis Rich of Bell Laboratories in the United States finally designed a new language based on the B language . He took the second letter of BCPL as the name of this language, which is the C language.
In early 1973, the main body of the C language was completed. Thompson and Rich couldn't wait to start completely rewriting UNIX with it . At this time, the joy of programming made them completely forget about the "Space Travel" and devote themselves to the development of UNIX and C language. With the development of UNIX, the C language itself is constantly improving. Until 2020, various versions of the UNIX kernel and peripheral tools still use the C language as the main development language, and many of them inherit the codes of Thompson and Rich. [6]
During development, they also considered porting UNIX to other types of computers. The powerful portability of C language is here. Neither machine language nor assembly language is portable, and programs developed for x86 cannot run on machines such as Alpha , SPARC , and ARM . The C language program can be used on a processor of any architecture , as long as the processor of that architecture has a corresponding C language compiler and library, and then the C source code is compiled and linked into a target binary file, which can be used architecture the processor runs on. [6]
In 1977, Dennis Ritchie published the C language compilation text "Portable C Language Compiler" that does not depend on the specific machine system.
The C language continues to develop. In 1982, many people of insight and the American National Standards Institute ( ANSI ) decided to establish a C standard committee to establish a C language standard in order to make the C language develop healthily. The committee is composed of hardware vendors, compiler and other software tool manufacturers, software designers, consultants, academics, C language authors, and application programmers. In 1989, ANSI released the first complete C language standard - ANSI X3.159-1989, referred to as "C89", but people are also used to call it "ANSI C". C89 was adopted by the International Standard Organization ( ISO ) without change in 1990. The official name given by ISO is: ISO/IEC 9899, so ISO/IEC9899:1990 is often referred to as "C90" . In 1999, after making some necessary amendments and improvements, ISO released a new C language standard, named ISO/IEC 9899:1999, referred to as " C99 ". On December 8, 2011, ISO officially released a new standard called ISO/IEC9899:2011, referred to as " C11 ".
The picture below is the programming language ranking list compiled by TIOBE in October 2014 based on the usage of programming languages in enterprises. Programmers can understand the value of their programming skills in order to keep up with the programming trend. This ranking list can also be used as a reference for beginners to choose their future development direction.
This picture is also from TIOBE. From this picture, you can find that from 2002 to the present, the proportion of C language in programming has remained stable, while the Java language has shown a downward trend, and the two will often compete for supremacy.
C language program structure
The C program creation process has four basic steps:
1. Edit 2. Compile 3. Link 4. Execute
Simple structure of C language
1. Preprocessing directive 2. main()Function 3. Program frame 4. printf() Function
Literature citations:
Baidu Encyclopedia
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