A brief History of C

The beginning

In 1966 Martin Richards of the University of Cambridge developed a programming language called Basic Combined Programming Language (BCPL).

In 1969 Kenneth Lane Thompson (Ken Thompson) developed a stripped-down version of the BCPL programming language called 'B' for Bell Laboratories. Currently Thompson is working with Google.
The 'C' Language has been developed by Dennis M. Ritchie inspired by the language B, for use with the UNIX operating system in 1972. He returned from the main function on October 12, 2011.
The language was originally designed to help the development of Unix Operating System. The UNIX is one of the first OS developed in a high level language.

The earlier version of C has been changed many times to incorporate powerful features of different computer architectures. One of such feature is the ‘struct’ type added in 1973.

By the first edition of the book, 'The C Programming Language' by Brian Kernighan and Dennis Ritchie in 1978, the language got its first written specification. The version of the language described in this book is known as K&R.

In the book, they have introduced many additional features to the language such as

-           I/O libraries

-          ‘long’ and ‘unsigned’ type modifiers.

ANSI/ISO C90

In 1983, the American National Standards Institute (ANSI) formed a committee, to establish a standard specification of C. And in 1989, the first draft of the standard was published. This version often referred to as ANSI C or C89.

In 1990, International Organization for Standardization (ISO) adopts the ANSI standard of C language as ISO/IEC 9899:1990 and this is referred to as C90. (Both C89 and C90 are the same language). ANSI no longer develops the C standard independently, but defers to the ISO C standard.

ISO C99

The C standard was further revised and lead to the publication of ISO/IEC 9899:1999 in 1999, which is commonly referred to as "C99". C99 introduced several new features in the language and some of them are

-          inline functions

-          long long int complex data types

-          variable-length arrays

-          variadic macros

-          support for one-line comments beginning with //

Some of these features are borrowed from other languages like C++, but After C99, C is no more considered as a subset of C++. C supports many features not included in C++.

-          Implicit casting of ‘void’ pointers

-          ‘long long’ type modifier

-          Calling ‘main’ function recursively

-          ‘restrict’ keyword

-          Variadic macros

-          Variable length arrays

-          Flexible array members

-          Designated initializers

-          Compound literals

Links

The C99 standard is available here or here.

Most used free compilers of C/C++: MingW and Visual C++ Express Edition.

Some FOSS IDEs for MingW: CodeBlocks, Dev-C++, NotePad++ (More like an editor) and TextPad (my favorite, and again an editor, you may read this: How to configure TextPad as MingW IDE)

Comparison of different Visual Studio editions.

C1X

In 2007, the ISO started revising the C standard, informally called "C1X".

For ISO, the major guiding principles for drafting the standard are

-          Existing code is important, existing implementations are not.

-          C code can be portable.

-          C code can be non-portable.

-          Avoid "quiet changes."

-          A standard is a treaty between implementer and programmer.

-          Keep the spirit of C. And below are some of the facets of the spirit of C:

ü  Trust the programmer.

ü  Don't prevent the programmer from doing what needs to be done.

ü  Keep the language small and simple.

ü  Provide only one way to do an operation.

ü  Make it fast, even if it is not guaranteed to be portable.

Examples

The examples given below are linked from the above sessions. Make use of those links for better understanding. Avoidance of these examples don’t affect the flow of the article and can be skipped if found difficult.

inline functions

Actual source code	After inline expansion

Inline is exactly a request to the compiler for expanding the code inline; it may or may not do it according to the implementation. ‘inline’ functions are not same as macros. Macros are handled by the preprocessor and they do not have a type check.

long long int complex data types

 

Output: 1, 2, 4, 4, 8

A simple rule of the size of the integer types is

All sizes are in bytes.

Variable-length arrays

This is, what exactly the name suggest

Is valid in C!

variadic macros

A macro can be declared to accept a variable number of arguments much as a function can. The syntax for defining the macro is similar to that of a function.

 

Support for one-line comments

Implicit casting of ‘void’ pointer

The void* can be converted to any one without a typecast. Example of an impact is ‘malloc’. The old return type of the same function was char* and after the introduction of void in C, it is changed to void*. Now the usage should be:

And not

Calling ‘main’ function recursively

This is not allowed in C++. Even there is little usage, it is supported in C.

The above code will just make an infinite loop.

The major use of this feature is in obfuscation.

‘restrict’ keyword

This keyword is used to tell the compiler that an object is accessed only through the ‘restrict’ qualified pointer. This allows the compiler to perform certain optimizations. And accessing such an object using another pointer will cause undefined behavior.

Flexible array members

A structure can have an array member at the end of it without specifying a size. While allocating memory for the structure object, by allocating more memory for this array member one can extend the size of it.

Here, the array member ‘data’ of object ‘p’ will have 10 characters length and that of ‘q’ will have 15 characters length.

Designated initializers

This feature allows initializing the members of an array or a structure in any order.

Both the above statements are equivalent initializations.

Similarly for a structure

are equal.

Compound literals

A compound literal looks like a cast containing an initializer. Its value is an object of the type specified in the cast, containing the elements specified in the initializer

Is equivalent to:

Future

The language has done its role to build and shape the computer era. Born in Bell and Brought up by Brilliants! The beauty of C is it believes her programmers. So, if anyone feels that C lacks a feature which helps you from doing something nasty, woke up, you are a programmer, not a school kid! And C is a real programmer's language.