Examples of Simple C Program

Example 1: Adding Two Integers 

Source Code:

 /* Fig. 2.5: fig02_05.c
2 Addition program */
#include <stdio.h>
/* function main begins program execution */
int main( void )
{
int integer1; /* first number to be input by user */
int integer2; /* second number to be input by user */
int sum; /* variable in which sum will be stored */
printf( "Enter first integer\n" ); /* prompt */
scanf( "%d", &integer1 ); /* read an integer */
printf( "Enter second integer\n" ); /* prompt */
scanf( "%d", &integer2 ); /* read an integer */
sum = integer1 + integer2; /* assign total to sum */
printf( "Sum is %d\n", sum ); /* print sum */
system("pause");
return 0; /* indicate that program ended successfully */
} /* end function main */

Output:

Example 2: Decision Making: Equality and Relational Operators

Source Code:

/* Fig. 2.13: fig02_13.c
Using if statements, relational  3 operators, and equality operators */
 #include <stdio.h>
 /* function main begins program execution */
 int main( void )
 {
 int num1; /* first number to be read from user */
 int num2; /* second number to be read from user */
 
 printf( "Enter two integers, and I will tell you\n" );
 printf( "the relationships they satisfy: \n" );
 scanf( "%d%d", &num1, &num2 ); /* read two integers */
 
 if ( num1 == num2 ) { 
 printf( "%d is equal to %d\n", num1, num2 );
 } /* end if */
 if ( num1 != num2 ) {
 printf( "%d is not equal to %d\n", num1, num2 );
 } /* end if */
 if ( num1 < num2 ) {
 printf( "%d is less than %d\n", num1, num2 );
 } /* end if */
 if ( num1 > num2 ) {
 printf( "%d is greater than %d\n", num1, num2 );
 } /* end if */
 if ( num1 <= num2 ) {
 printf( "%d is less than or equal to %d\n", num1, num2 );
 } /* end if */
 if ( num1 >= num2 ) {
 printf( "%d is greater than or equal to %d\n", num1, num2 );
 } /* end if */
 system("pause");
 return 0; /* indicate that program ended successfully */
 
 } /* end function main */

Output: