Java Modulo

In this section, we will discuss the Java modulo operator.

Java Modulo Operator

In mathematics, there is basically four arithmetic operators addition (+), subtraction (-), multiplication (*), and division (/). In programming, except for these four operators, there is another operator called modulo or modulus operator. It is represented by the percentage symbol (%).

It is used to determine the remainder. It requires two operands. It divides the left-hand operand by the right-hand operand and gives the remainder. For example:

We can also use it with the assignment operator (=). For example,

It takes modulus using two operands and assigns the result to left operand (a).

If it appears in an expression, we must solve the expression left to right. For example, consider the following expression.

If the number is completely divided, it returns gives 0 as the result. For example, 25%5 gives 0.

Let's see some other examples of modulo operator.

12%2=0

12%5=2

-12%-5=-2

-12%5=3

12%-5=-3

Uses of Modulo Operator

The most common use case for the modulo operator is to find out if a given number is odd or even.
Another use of the modulo operator is to keep track of the index of the next free spot in a circular array.

For a programmer, it is very important to know how to use the modulo operator because it plays a vital role to build logic like reverse a number, find even odd, palindrome, and many more. We can also use it to find the last digit of a number.

Suppose, the given number is 5678 and we have to find the last digit of the number. As we know the modulo operator determines the remainder, so we will divide the given number by 10. Therefore, we get 8 as the remainder and the last digit.

We can also use the modulo operator with floating-point numbers. For example,

Using Modulo Operator in a Java Programs

The following Java program demonstrates the use of the modulo operator in Java.

ModuloOperatorExample1.java

public class ModuloOperatorExample1
{
public static void main(String args[]) 
{
int a = 13;
int b=2;
b = a%b;  
System.out.println("Remainder: "+b);
}
}

Output:

Remainder: 1

ModuloOperatorExample2.java

public class ModuloOperatorExample2
{
public static void main(String args[]) 
{
double c=8.9, d=2.7, remainder;
remainder = c%d;  
System.out.println("Remainder: "+remainder);
}
}

Output:

Remainder: 0.7999999999999998

Difference Between Modulo and Division Operator

The major difference between modulo and division operators is that the modulo (%) operator gives the remainder while the division (/) operator gives the quotient.

The following Java program will clear the concept of modulo and division operator.

ModuloOperatorExample3.java

public class ModuloOperatorExample3
{
public static void main(String args[]) 
{
int a = 13;
int b=2;
b =a/b; 
System.out.println("Quotient: "+b);
b = a%b;  
System.out.println("Remainder: "+b);
}
}

Output:

Quotient: 6
Remainder: 1

Java Program to Find Remainder Without Using the Modulo Operator

RemainderWithoutModulo.java

public class RemainderWithoutModulo 
{
//function finds the remainder without using the modulo operator
static int findRemainder(int n, int div)
{
//calculates remainder and returns the same    
return (n - div * (n / div));
}
//driver code
public static void main(String args[])
{
//calls the function and prints the result    
System.out.println("Remainder: "+findRemainder(345456, 25));
}
}

Output: