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C Language Standard

In this blog you will learn about the standard of the C language. The previous blog was about the structure of a program in C, which you can find here.


By definition, a standard is something established by authority as a model or point of reference. Just like the standard units of measurement, a standard for the programming language C was also required. This need arose because after C was developed, many professional programmers started making their own additions to it. This led to a number of variations of C being available for a programmer to choose from, but none of them was the real one. So, there was an urgent need for standardization.


Previous Standards of C:


The first standard was informal, and called K&R C after Brian Kernighan and Dennis Ritchie. It added some new features like the data types long int and unsigned int, and the compound assignment operator. It also proposed a standardized I/O library. There are only 28 keywords in K&R C.


Even with K&R C, it was important for some standards organisation to come up with an official standard for C. The American National Standard Institute (ANSI) undertook the task, and as a result, ANSI C was developed. Keywords like const, enum, signed, void and volatile were introduced in ANSI C. It is also called C89, C90 or ISO C. It remains one of the very popular standards of C language. Almost all C compilers support features of ANSI C.


In 1999, a new standard of C was developed, which was called ISO/IEC 9899:1999, or more simply, C99. It added a few more keywords to ANSI C like inline and restrict, along with new header files like <stdbool.h> <complex.h>, etc.


Another standard, which is being developed in parallel to the other standards, is the Embedded C. The Embedded C was developed for the needs of embedded system programmers. It is mostly similar to the normal C, with some additional features. It has the advantage that it is simpler and easier to learn.


Current Standard of C:


The current and latest C programming language standard is called C11. It was adopted in 2011, hence the name. The document describing the C11 standard is called ISO/IEC 9899:2011. It added seven more keywords to C, making the total count of keywords 44.

 

Happy coding!

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