Mod Operator (Visual Basic)


Updated: July 20, 2015

For the latest documentation on Visual Studio 2017, see Visual Studio 2017 Documentation.

Divides two numbers and returns only the remainder.

number1 Mod number2  

Required. Any numeric expression.

Required. Any numeric expression.

All numeric types. This includes the unsigned and floating-point types and Decimal.

The result is the remainder after number1 is divided by number2. For example, the expression 14 Mod 4 evaluates to 2.

If either number1 or number2 is a floating-point value, the floating-point remainder of the division is returned. The data type of the result is the smallest data type that can hold all possible values that result from division with the data types of number1 and number2.

If number1 or number2 evaluates to Nothing, it is treated as zero.

Related operators include the following:

  • The \ Operator (Visual Basic) returns the integer quotient of a division. For example, the expression 14 \ 4 evaluates to 3.

  • The / Operator (Visual Basic) returns the full quotient, including the remainder, as a floating-point number. For example, the expression 14 / 4 evaluates to 3.5.

If number2 evaluates to zero, the behavior of the Mod operator depends on the data type of the operands. An integral division throws a DivideByZeroException exception. A floating-point division returns NaN.

The expression a Mod b is equivalent to either of the following formulas:

a - (b * (a \ b))

a - (b * Fix(a / b))

When you work with floating-point numbers, remember that they do not always have a precise representation in memory. This could lead to unexpected results from certain operations, such as value comparison and the Mod operator. For more information, see Troubleshooting Data Types.

The Mod operator can be overloaded, which means that a class or structure can redefine its behavior. If your code applies Mod to an instance of a class or structure that includes such an overload, be sure you understand its redefined behavior. For more information, see Operator Procedures.

The following example uses the Mod operator to divide two numbers and return only the remainder. If either number is a floating-point number, the result is a floating-point number that represents the remainder.

        Debug.WriteLine(10 Mod 5)
        ' Output: 0
        Debug.WriteLine(10 Mod 3)
        ' Output: 1
        Debug.WriteLine(-10 Mod 3)
        ' Output: -1
        Debug.WriteLine(12 Mod 4.3)
        ' Output: 3.4
        Debug.WriteLine(12.6 Mod 5)
        ' Output: 2.6
        Debug.WriteLine(47.9 Mod 9.35)
        ' Output: 1.15

The following example demonstrates the potential imprecision of floating-point operands. In the first statement, the operands are Double, and 0.2 is an infinitely repeating binary fraction with a stored value of 0.20000000000000001. In the second statement, the literal type character D forces both operands to Decimal, and 0.2 has a precise representation.

        firstResult = 2.0 Mod 0.2
        ' Double operation returns 0.2, not 0.
        secondResult = 2D Mod 0.2D
        ' Decimal operation returns 0.

Arithmetic Operators
Operator Precedence in Visual Basic
Operators Listed by Functionality
Troubleshooting Data Types
Arithmetic Operators in Visual Basic
\ Operator (Visual Basic)