C PROGRAM • DECISION MAKING

Check Whether a Number Is Even or Odd

Use the remainder operator and an if-else decision to classify an integer.

Beginnerif-elseModulusCondition

PROBLEM UNDERSTANDING

Input and expected output

Sample input

Sample output

Enter an integer: 17
17 is odd.

C PROGRAM

Complete program

#include <stdio.h>

int main(void)
{
    int number;
    printf("Enter an integer: " );
    scanf("%d", &number);
    if (number % 2 == 0)
        printf("%d is even.\n", number);
    else
        printf("%d is odd.\n", number);
    return 0;
}

Integer

CURRENT STEP

Select Start to trace this program.

VARIABLES

Scope	Name	Value
Not started

CALL STACK

main()

PROGRAM OUTPUT

Waiting to run…

0%Step 0 of 0

PROGRAM EXPLANATION

Algorithm and explanation

Read an integer.
Calculate number % 2.
If the remainder is zero, print even; otherwise print odd.

An even integer is exactly divisible by 2. Therefore number % 2 gives 0 for even values and a non-zero remainder for odd values.

EFFICIENCY

Time and space complexity

Time complexity

O(1)

Auxiliary space

O(1)

DEBUGGING CHECKLIST

Common mistakes

Check this

Using = instead of == in the condition.

Check this

Using division instead of the remainder operator.