Structure Of C Programs

 All the C Program are divided into many parts such as :

•        Preprocessor Commands

•        Functions

•        Variables

•        Statements and Expressions

•        Comments

Preprocessor Commands :-

           Preprocessor Command is not a part of the compiler of c language but it is a diffrent step in the compilation time. All preprocessor commands starts with a (#) symbol.

Example :-

#define               Substitutes a preprocessor macro      

#include             Inserts a particular header from another file  

#undef                Undefines a preprocessor macro        

#ifdef                  Returns true if this macro is defined     

#ifndef                Returns true if this macro is not defined

#if                       Tests if a compile time condition is true

#else                    The alternative for #if

#elif                     #else an #if in one statement

#endif                  Ends preprocessor conditional

#error                  Prints error message on stderr

#pragma              Issues special commands to the compiler, using a standardized method

Main() Function :-

                we all know why main  function is used in c programs because when we run the program at that time program execution start with the main Function.

Syntax :-

int main()

{

// code write here

return 0;

}

Comments :-

         Comments are the statements that are ignored by the  compiler.

Syntax :-

                Multiline Comments :-

                /*    

                                  Comments statement that put here

                */

                Singleline Comments :-

                //     Comment statement put here for single line comments

Example of Hello World Program :-

#include<stdio.h>            //Preprocessor Commands

int main()                         //main()   program execution start to here

{

/* hello word program in c    */         //comments statements

printf(“Hello World…..\n”);    

return 0;                      

}