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Expression::AndAlso Method (Expression, Expression)

Creates a BinaryExpression that represents a conditional AND operation that evaluates the second operand only if the first operand evaluates to true.

Namespace:  System.Linq.Expressions
Assembly:  System.Core (in System.Core.dll)

public:
static BinaryExpression^ AndAlso(
	Expression^ left, 
	Expression^ right
)

Parameters

left
Type: System.Linq.Expressions::Expression

A Expression to set the Left property equal to.

right
Type: System.Linq.Expressions::Expression

A Expression to set the Right property equal to.

Return Value

Type: System.Linq.Expressions::BinaryExpression
A BinaryExpression that has the NodeType property equal to AndAlso and the Left and Right properties set to the specified values.

ExceptionCondition
ArgumentNullException

left or right is nullptr.

InvalidOperationException

The bitwise AND operator is not defined for left.Type and right.Type.

-or-

left.Type and right.Type are not the same Boolean type.

The resulting BinaryExpression has the Method property set to the implementing method. The Type property is set to the type of the node. If the node is lifted, the IsLifted and IsLiftedToNull properties are both true. Otherwise, they are false. The Conversion property is nullptr.

The following information describes the implementing method, the node type, and whether a node is lifted.

The following rules determine the implementing method for the operation:

  • If the Type property of either left or right represents a user-defined type that overloads the bitwise AND operator, the MethodInfo that represents that method is the implementing method.

    NoteNote

    The conditional AND operator cannot be overloaded in C# or Visual Basic. However, the conditional AND operator is evaluated by using the bitwise AND operator. Thus, a user-defined overload of the bitwise AND operator can be the implementing method for this node type.

  • Otherwise, if left.Type and right.Type are Boolean types, the implementing method is nullptr.

If the implementing method is not nullptr:

  • If left.Type and right.Type are assignable to the corresponding argument types of the implementing method, the node is not lifted. The type of the node is the return type of the implementing method.

  • If the following two conditions are satisfied, the node is lifted and the type of the node is the nullable type that corresponds to the return type of the implementing method:

    • left.Type and right.Type are both value types of which at least one is nullable, and the corresponding non-nullable types are equal to the corresponding argument types of the implementing method.

    • The return type of the implementing method is a non-nullable value type.

If the implementing method is nullptr:

  • left.Type and right.Type are the same Boolean type.

  • If left.Type and right.Type are non-nullable, the node is not lifted. The type of the node is the result type of the predefined conditional AND operator.

  • If left.Type and right.Type are nullable, the node is lifted. The type of the node is the nullable type that corresponds to the result type of the predefined conditional AND operator.

The following code example shows how to create an expression that performs a logical AND operation on its two operands only if the first operand evaluates to true.

No code example is currently available or this language may not be supported.

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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