Examples of simple c programs

Example 1:

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 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.

Example 2:

C Program to Add Two Integers

In this program, user is asked to enter two integers. Then, the sum of those two integers is stored in a variable and displayed on the screen.

#include <stdio.h>
int main()
{
    int firstNumber, secondNumber, sumOfTwoNumbers;
    
    printf("Enter two integers: ");

    // Two integers entered by user is stored using scanf() function
    scanf("%d %d", &firstNumber, &secondNumber);

    // sum of two numbers in stored in variable sumOfTwoNumbers
    sumOfTwoNumbers = firstNumber + secondNumber;

    // Displays sum      
    printf("%d + %d = %d", firstNumber, secondNumber, sumOfTwoNumbers);

    return 0;
}

Output

Enter two integers: 12
11
12 + 11 = 23

In this program, user is asked to enter two integers. Two integers entered by the user is stored in variables firstNumber and secondNumber respectively. This is done using scanf() function.

Then, variables firstNumber and secondNumber are added using + operator and the result is stored in sumOfTwoNumbers.

Finally, the sumofTwoNumbers is displayed on the screen using printf() function.