First lesson: C "Hello World!" Program

A simple C program to display "Hello, World!" on the screen. Since, it's a very simple program, it is often used to illustrate the syntax of a programming language.

To understand this example, you should have the knowledge of following C programming topics:

• C Programming Input Output (I/O): printf() and scanf()

Program to Display "Hello, World!"

#include <stdio.h>
int main()
{
   // printf() displays the string inside quotation
   printf("Hello World!");
   return 0;
}

Output

Hello, World!

How "Hello, World!" program works?

• The #include <stdio.h> is a preprocessor command. This command tells compiler to include the contents of stdio.h (standard input and output) file in the program.
  The stdio.h file contains functions such as scanf() and print() to take input and display output respectively.
  If you use printf() function without writing #include <stdio.h>, the program will not be compiled.
• The execution of a C program starts from the main() function.
• The printf() is a library function to send formatted output to the screen. In this program, the printf() displays Hello, World! text on the screen.
• The return 0; statement is the "Exit status" of the program. In simple terms, program ends with this statement.