C (programming language)

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The C programming language is a well-used and important computer programming language. C was developed in the early 1970s by Ken Thompson and Dennis Ritchie at Bell Labs, and they used it to improve the UNIX operating system. It is still used a lot today. C is a procedural language, which means that people write their programs 11527178 as a series of step-by-step instructions. C is a compiled language, which means that the computer source code, written in C, gets read to make some machine code that a computer chip can actually execute, and that machine code is released.

Because the ideas behind C are like the ideas use to the design of the computer, the compiler (program builder) can generate fast machine code for the computer. The language itself has very few keywords, and most things are done using libraries, which are collections of code made to be reused. C has a big standard library called stdio, which stands for standard input/output.

C has a variety of uses:

  • writing embedded systems like the code that runs inside a computer mouse, or a car headlight.
  • writing device drivers like the code inside a laptop computer that interacts with the touchpad or the microphone
  • writing protocol stacks like the code that allows one computer to talk to other computers on the internet.
  • writing operating systems, such as Linux, MacOS and UNIX, and the utilities that come with those operating systems.

C standards[change | change source]

There are three successive standards for the C programming language ANSI C, ISO C and Standard C which are published by the American National Standards Institute (ANSI) and the International Organization for Standardization (ISO).

C is available for many different types of computers. This is why C is called a "portable" language. A program that is written in C and that respects certain limitations can be compiled for most platforms, and all in mainstream use.

The syntax of C has also influenced many other programming languages, such as C++, C#, and Java, and many more programming languages we use nowadays.

Example code[change | change source]

Here is an example of a program written in C. When built and run it will show "Hello world!", followed by a new line on the computer screen.

#include <stdio.h>

int main() {
    printf("Hello world!\n");
    return 0;
}
  • #include <stdio.h> gets the standard input/output tools ready for the program to use. This allows text to be displayed (output).
  • int main() is called the main function, and it is where the first code starts being run in a C program.
  • printf("Hello world!\n"); is what displays text, in this case "Hello world!" with a new line (\n) at the end.
  • return 0; tells the computer that the program finished and did not run into problems.

Related pages[change | change source]

Other websites[change | change source]