Expression.Negate Method (Expression)
Creates a UnaryExpression that represents an arithmetic negation operation.
Assembly: System.Core (in System.Core.dll)
The Method property of the resulting UnaryExpression is 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 following rules determine the implementing method for the operation:
If expression.Type is a user-defined type that defines the unary minus operator, the MethodInfo that represents that operator is the implementing method.
Otherwise, if expression.Type is a numeric type, the implementing method is null.
Node Type and Lifted versus Non-Lifted
If the implementing method is not null:
If expression.Type is assignable to the argument type 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:
expression.Type is a nullable value type and the corresponding non-nullable value type is equal to the argument type of the implementing method.
The return type of the implementing method is a non-nullable value type.
If the implementing method is null, the type of the node is expression.Type. If expression.Type is non-nullable, the node is not lifted. Otherwise, the node is lifted.
The following example demonstrates how to create an expression that represents an arithmetic negation operation.
// Add the following directive to your file: // using System.Linq.Expressions; // This expression represents a negation operation. Expression negateExpr = Expression.Negate(Expression.Constant(5)); // The following statement first creates an expression tree, // then compiles it, and then runs it. outputBlock.Text += Expression.Lambda<Func<int>>(negateExpr).Compile()() + "\n"; // This code example produces the following output: // // -5
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