subtraction-assignment-operator.md

title	-= Operator (Visual Basic)
ms.date	07/20/2015
ms.prod	.net
ms.reviewer
ms.suite
ms.technology	devlang-visual-basic
ms.topic	article
f1_keywords	vb.-=
helpviewer_keywords	-= operator [Visual Basic] assignment statements [Visual Basic], compound statements [Visual Basic], compound assignment operator -= compound assignment statements [Visual Basic]
ms.assetid	5ead0c37-ae50-48f7-8435-8e341d81cae1
caps.latest.revision	19
author	dotnet-bot
ms.author	dotnetcontent

-= Operator (Visual Basic)

Subtracts the value of an expression from the value of a variable or property and assigns the result to the variable or property.

Syntax

variableorproperty -= expression  

Parts

variableorproperty
Required. Any numeric variable or property.

expression
Required. Any numeric expression.

Remarks

The element on the left side of the -= operator can be a simple scalar variable, a property, or an element of an array. The variable or property cannot be ReadOnly.

The -= operator first subtracts the value of the expression (on the right-hand side of the operator) from the value of the variable or property (on the left-hand side of the operator). The operator then assigns the result of that operation to the variable or property.

Overloading

The - Operator (Visual Basic) can be overloaded, which means that a class or structure can redefine its behavior when an operand has the type of that class or structure. Overloading the - operator affects the behavior of the -= operator. If your code uses -= on a class or structure that overloads -, be sure you understand its redefined behavior. For more information, see Operator Procedures.

Example

The following example uses the -= operator to subtract one Integer variable from another and assign the result to the latter variable.

[!code-vbVbVbalrOperators#11]

See Also

- Operator (Visual Basic)
Assignment Operators
Arithmetic Operators
Operator Precedence in Visual Basic
Operators Listed by Functionality
Statements