Modulo Operator (%) in C/C++ with Examples

The modulo operator, denoted by %, is an arithmetic operator.

The modulo division operator produces the remainder of an integer division.

Syntax: If x and y are integers, then the expression:

x % y

produces the remainder when x is divided by y.

Return Value:

• If y completely divides x, the result of the expression is 0.
• If y is not completely divisible by x, then the result will be the remainder in the range [1, x-1].
• If x is 0, then division by zero is a compile-time error.

For example: Consider the following code:

3
1
0

Restrictions of the modulo operator:
The modulo operator has quite some restrictions or limitations.

1. The % 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 a error:
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   // Program to illustrate the // working of modulo operator    #include <stdio.h>    int main(void) {        // To store two integer values     float x, y;        // To store the result of     // the modulo expression     float result;        x = 2.3;     y = 1.5;     result = x % y;     printf("%f", result);        return 0; }

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   Compilation Error:

   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;
                   ^           
   

2. The sign of the result for modulo operator is machine-dependent for negative operands, as the action takes as a result of underflow or overflow.
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   // Program to illustrate the // working of the modulo operator    #include <stdio.h>    int main(void) {        // To store two integer values     int x, y;        // To store the result of     // the modulo expression     int result;        x = -3;     y = 4;     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; }

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   Output:

   -3
   0
   -3
   

   Note: Some compilers may show the result of the expression as 1 and other may show -1. It depends on the compiler.

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