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Expression.Or Method (Expression, Expression)

Creates a BinaryExpression that represents a bitwise OR operation.

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

public static BinaryExpression Or(
	Expression left,
	Expression right
)

Parameters

left
Type: System.Linq.Expressions.Expression
An Expression to set the Left property equal to.
right
Type: System.Linq.Expressions.Expression
An Expression to set the Right property equal to.

Return Value

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

ExceptionCondition
ArgumentNullException

left or right is null.

InvalidOperationException

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

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

Implementing Method

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 OR operator, the MethodInfo that represents that method is the implementing method.

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

Node Type and Lifted versus Non-Lifted

If the implementing method is not null:

  • 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 null:

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

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

The following code example shows how to create an expression that represents a logical OR operation.


// Add the following directive to your file:
// using System.Linq.Expressions;  

// This expression perfroms a logical OR operation
// on its two arguments. Both arguments must be of the same type,
// which can be boolean or integer.             
Expression orExpr = Expression.Or(
    Expression.Constant(true),
    Expression.Constant(false)
);

// Print out the expression.
Console.WriteLine(orExpr.ToString());

// The following statement first creates an expression tree,
// then compiles it, and then executes it.       
Console.WriteLine(Expression.Lambda<Func<bool>>(orExpr).Compile()());

// This code example produces the following output:
//
// (True Or False)
// True


.NET Framework

Supported in: 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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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