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# C Program for Modulo Operator: Check Divisibility and Print Remainder

In C programming, the modulo operator (`%`) is a handy tool for determining the remainder when dividing two numbers. This is useful when you want to check if a number is divisible by another or when you need to find the remainder of a division operation. In this blog post, we will explain how the modulo operator works and provide a simple C program to demonstrate its usage.

#### What is the Modulo Operator?

The modulo operator (`%`) in C returns the remainder of the division of one number by another. For example:

• `10 % 3` returns `1` because when you divide 10 by 3, the remainder is 1.
• `9 % 3` returns `0` because 9 is evenly divisible by 3 with no remainder.

The modulo operator is often used in programming to check for divisibility and to calculate remainders.

#### Syntax of Modulo Operator:

``result = a % b;``

Here, `a` is the dividend, and `b` is the divisor. The `result` will store the remainder of `a` divided by `b`.

#### Example: C Program to Check Divisibility and Print Remainder

Let’s write a C program that uses the modulo operator to check whether a number is divisible by another and print the remainder.

``````#include <stdio.h>

int main() {
int num1, num2, remainder;

// Input two numbers
printf("Enter two integers: ");
scanf("%d %d", &num1, &num2);

// Check if num2 is not zero to avoid division by zero
if (num2 != 0) {
// Calculate remainder using modulo operator
remainder = num1 % num2;

// Check if the number is divisible
if (remainder == 0) {
printf("%d is divisible by %d.\n", num1, num2);
} else {
printf("%d is not divisible by %d. Remainder: %d\n", num1, num2, remainder);
}
} else {
printf("Division by zero is not allowed.\n");
}

return 0;
}``````

#### Explanation of the Program:

• Input: The program prompts the user to input two integers: `num1` (the number to be divided) and `num2` (the divisor).
• Modulo Operation: The modulo operator (`%`) is used to find the remainder when `num1` is divided by `num2`.
• Divisibility Check: If the remainder is `0`, the program outputs that `num1` is divisible by `num2`. Otherwise, it prints the remainder.
• Error Handling: If the user enters `0` as the second number (`num2`), the program avoids division by zero and outputs an error message.

#### Sample Output

If the user enters `10` and `3` as input:

``````Enter two integers: 10 3
10 is not divisible by 3. Remainder: 1``````

If the user enters `9` and `3` as input:

``````Enter two integers: 9 3
9 is divisible by 3.``````

If the user enters `10` and `0` as input:

``````Enter two integers: 10 0
Division by zero is not allowed.``````

#### When to Use the Modulo Operator

The modulo operator is especially useful in the following scenarios:

1. Divisibility Checks: To check whether one number is divisible by another.
2. Cycling Through Values: For example, when iterating over a fixed-size array in a circular manner.
3. Finding Remainders: When you need to calculate the remainder after division, such as in time calculations.

The modulo operator is a powerful tool in C programming for performing mathematical operations involving division. By using it, you can easily check if a number is divisible by another and calculate the remainder. This is a simple yet fundamental operation that is widely used in programming.