Last Updated : 30 Oct, 2023
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In C or C++, the modulo operator (also known as the modulus operator), denoted by %, is an arithmetic operator. The modulo division operator produces the remainder of an integer division which is also called the modulus of the operation.
Syntax of Modulus Operator
If x and y are integers, then the expression:
x % y;
pronounced as “x mod y”. For example, 10 % 2 will be pronounced as ” Ten mod Two”.
Return Value of Modulo Operator
- If y completely divides x, the result of the expression is 0.
- If x is not completely divisible by y, then the result will be the remainder in the range [0, y-1]
- (x % y) < (x / 2) ………if (x >= y)
- (x % y) = x ……… if (x < y)
- If y is 0, then division by zero is a compile-time error.
Example of Modulo Operator
Below is the C/C++ program to demonstrate the working of the modulo operator:
C++
// C++ Program to demonstrate the working of modulo operator
#include <iostream>
using namespace std;
// Driver code
int main(void)
{
int x, y;
int result;
x = 3;
y = 4;
// using modulo operator
result = x % y;
cout << result << endl;
result = y % x;
cout << result << endl;
// for different values
x = 4;
y = 2;
result = x % y;
cout << result;
return 0;
}
// This code is contributed by Mayank Tyagi
C
// C Program to illustrate the working of modulo operator
#include <stdio.h>
int main(void)
{
int x, y;
int result;
x = 3;
y = 4;
// using modulo operator
result = x % y;
printf("%d", result);
result = y % x;
printf("\n%d", result);
// for different values
x = 4;
y = 2;
result = x % y;
printf("\n%d", result);
return 0;
}
Restrictions on the Modulo Operator
The modulo operator has few restrictions or limitations on it. The % modulus operator cannot be applied to floating-point numbers i.e. float or double. If you try to use the modulo operator with floating-point constants or variables, the compiler will produce an error.
Example 1: C/C++ program to demonstrate the restrictions of the modulo operator.
C++
// C++ Program to demonstrate the restrictions of modulo
// operator
#include <iostream>
using namespace std;
// Driver code
int main()
{
float x, y;
x = 2.3;
y = 1.5;
// modulo for floating point values
result = x % y;
cout << result;
return 0;
}
// This code is contributed by Harsh*t Srivastava
C
// C Program to illustrate the working of modulo operator
#include <stdio.h>
int main(void)
{
float x, y;
float result;
x = 2.3;
y = 1.5;
// modulo for floating point values
result = x % y;
printf("%f", result);
return 0;
}
Output
Compilation Error in C code :- prog.c: In function 'main':
prog.c:19:16: error:
invalid operands to binary % (have 'float' and 'float')
result = x % y;
^
Modulo Operator for Negative Operands
The sign of the result for the modulo operator is machine-dependent for negative operands, as the action takes as a result of underflow or overflow.
Example 2: C/C++ program to demonstrate the modulo operator for negative operands.
C++
// C++ Program to demonstrate the working of the modulo
// operator for negative operands
#include <iostream>
using namespace std;
// Driver code
int main(void)
{
int x, y;
int result;
x = -3;
y = 4;
// modulo for negative operands
result = x % y;
cout << result << endl;
x = 4;
y = -2;
result = x % y;
cout << result << endl;
x = -3;
y = -4;
result = x % y;
cout << result;
return 0;
}
// This code is contributed by Harsh*t Srivastava
C
// C Program to illustrate the working of the modulo
// operator with negative operands
#include <stdio.h>
int main(void)
{
int x, y;
int result;
x = -3;
y = 4;
// modulo for negative operands
result = x % y;
printf("%d", result);
x = 4;
y = -2;
result = x % y;
printf("\n%d", result);
x = -3;
y = -4;
result = x % y;
printf("\n%d", result);
return 0;
}
Output
-30-3
Note: The return value in this case is compiler dependent.
FAQs on Modulo Operator
Q1. Define mod.
Answer:
In C/C++ programming languages, mod refers to the mathematical operation in which one number is divided by another, and the remainder is returned.
It can be performed using modulo operator (%).
Q2. What is mod arithmetic?
Answer:
Mod arithmetic refers to the process in which a number keeps wrapping around a certain point in such a way that it is always less than that certain point. For example,
Consider the number n = 10 and the point p = 20.
When we increment n 10 times, it will be n = 20 but in modular arithmetic, it should ways be smaller that the specified point.One way to do that is to use modulo operator as:
n++;
n = n % p;To learn more about modular aritimatic, refer to the article – Modular Arithmatic
Q3. What is the difference between modulo and divide operator?
Answer:
The major difference between modulo and division operator is that:
- Modulo Operator (%) returns the remainder after dividing one number with other.
- Divide Operator (/) returns the quotient after dividing one number with other.
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