Rules to Write a C Program 

1.       'C' is a case sensitive language. It means lower case and upper case letters has different meaning. Usually all 'C' statements are entered in small case letters.

2.       Blank spaces may be inserted between two words to improve readability of the statements but no blank spaces are allowed within the word.

3.       A function name is always followed by a pair of parenthesis, as in case of main().

4.       The body of program is enclosed in braces   {} a pair of braces defines a block. A program may consist of several blocks.

5.       Each 'C' program ends with semicolon (;) to terminate statements.

6.       Each variable of program must be declared.

7.       Every program must have a special function named main ( ).the program execute from this function. The main ( )function can be located anywhere in the program but the general practice is to place it as the first function for better readability so that 'C' is many times called a free from language.

8.       We must take sure to include header files using # include directive when the program refers to special names and functions that is not define.

9.       Compiler directive such as define and include are the special instructions to the compiler to help it compile a program, they do not end with semicolon.