# Expression.Subtract Method (Expression, Expression)

Creates a BinaryExpression that represents an arithmetic subtraction operation that does not have overflow checking.

**Namespace:**System.Linq.Expressions

**Assembly:**System.Core (in System.Core.dll)

#### Parameters

- left
- Type: System.Linq.Expressions.Expression

An 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.BinaryExpressionA BinaryExpression that has the NodeType property equal to Subtract and the Left and Right properties set to the specified values.

Exception | Condition |
---|---|

ArgumentNullException | left or right is null. |

InvalidOperationException | The subtraction 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 selected implementing method for the operation:

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

Otherwise, if left.Type and right.Type are numeric 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 subtraction 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 subtraction operator.

The following code example shows how to create an expression that subtracts the argument from the first argument.

// Add the following directive to your file: // using System.Linq.Expressions; // This expression subtracts the second argument // from the first argument. // Both arguments must be of the same type. Expression subtractExpr = Expression.Subtract( Expression.Constant(12), Expression.Constant(3) ); // Print out the expression. outputBlock.Text += subtractExpr.ToString() + "\n"; // The following statement first creates an expression tree, // then compiles it, and then executes it. outputBlock.Text += Expression.Lambda<Func<int>>(subtractExpr).Compile().Invoke() + "\n"; // This code example produces the following output: // // (12 - 3) // 9

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