Structure of a C program

Basically a C program involves the following sections:

• Documentations
• Preprocessor Statements
• Global Declarations
• The main() function
  • Local Declarations
  • Program Statements & Expressions
• User Defined Functions

Sample code of C “Hello World” program:

Let’s begin with a simple C program code.

Example:

/*Writes the words "Hello World" on the screen */
  
#include<stdio.h>

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

or in different way

/*Writes the words "Hello World" on the screen */

#include<stdio.h>
#include<conio.h> 

void main()
{
    /* first C program */
    printf("Hello World\n");
    return;
}

Program Output:

The above example has been used to print “Hello World” on the screen.

Let’s look into various parts of the above C program.

/* Comments */	Comments are a way of explaining what makes a program. Comments are ignored by the compiler and used by others to understand the code.
#include<stdio.h>	stdio is standard for input / output, this allows us to use some commands which includes a file called stdio.h.
int/void main()	int/void is a return value, which will be explained in a while.
main()	The main() is the main function where program execution begins. Every C program must contain only one main function.
Braces	Two curly brackets “{…}” are used to group all statements together.
printf()	It is a function in C, which prints text on the screen.
return 0	At the end of the main function returns value 0.