C Program Structure

C Program Structure


A C program basically consists of the following parts −

  • Preprocessor Commands
  • Functions
  • Variables
  • Statements & Expressions
  • Comments

Let us look at a simple code that would print the words "Hello World" −

Live Demo

#include <stdio.h>

int main() {
   /* my first program in C */
   printf("Hello, World! \n");
   
   return 0;
}

Let us take a look at the various parts of the above program −

  • The first line of the program #include <stdio.h> is a preprocessor command, which tells a C compiler to include stdio.h file before going to actual compilation.

  • The next line int main() is the main function where the program execution begins.

  • The next line /*...*/ will be ignored by the compiler and it has been put to add additional comments in the program. So such lines are called comments in the program.

  • The next line printf(...) is another function available in C which causes the message "Hello, World!" to be displayed on the screen.

  • The next line return 0; terminates the main() function and returns the value 0.