# Expression.Equal Method

## Definition

Creates a BinaryExpression that represents an equality comparison.

## Overloads

Equal(Expression, Expression) |
Creates a BinaryExpression that represents an equality comparison. |

Equal(Expression, Expression, Boolean, MethodInfo) |
Creates a BinaryExpression that represents an equality comparison. The implementing method can be specified. |

## Equal(Expression, Expression)

Creates a BinaryExpression that represents an equality comparison.

```
public:
static System::Linq::Expressions::BinaryExpression ^ Equal(System::Linq::Expressions::Expression ^ left, System::Linq::Expressions::Expression ^ right);
```

`public static System.Linq.Expressions.BinaryExpression Equal (System.Linq.Expressions.Expression left, System.Linq.Expressions.Expression right);`

`static member Equal : System.Linq.Expressions.Expression * System.Linq.Expressions.Expression -> System.Linq.Expressions.BinaryExpression`

`Public Shared Function Equal (left As Expression, right As Expression) As BinaryExpression`

#### Parameters

- left
- Expression

An Expression to set the Left property equal to.

- right
- Expression

An Expression to set the Right property equal to.

#### Returns

A BinaryExpression that has the NodeType property equal to Equal and the Left and Right properties set to the specified values.

#### Exceptions

`left`

or `right`

is `null`

.

The equality operator is not defined for `left`

.Type and `right`

.Type.

### Examples

The following code example shows how to create an expression that checks whether the values of its two arguments are equal.

```
// Add the following directive to your file:
// using System.Linq.Expressions;
// This expression compares the values of its two arguments.
// Both arguments need to be of the same type.
Expression equalExpr = Expression.Equal(
Expression.Constant(42),
Expression.Constant(45)
);
// Print out the expression.
Console.WriteLine(equalExpr.ToString());
// The following statement first creates an expression tree,
// then compiles it, and then executes it.
Console.WriteLine(
Expression.Lambda<Func<bool>>(equalExpr).Compile()());
// This code example produces the following output:
//
// (42 == 45)
// False
```

```
' Add the following directive to your file:
' Imports System.Linq.Expressions
' This expression compares the values of its two arguments.
' Both arguments must be of the same type.
Dim equalExpr As Expression = Expression.Equal(
Expression.Constant(42),
Expression.Constant(45)
)
' Print the expression.
Console.WriteLine(equalExpr.ToString())
' The following statement first creates an expression tree,
' then compiles it, and then executes it.
Console.WriteLine(
Expression.Lambda(Of Func(Of Boolean))(equalExpr).Compile()())
' This code example produces the following output:
'
' (42 == 45)
' False
```

### Remarks

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 property is `true`

. Otherwise, it is `false`

. The IsLiftedToNull property is always `false`

. 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 equality operator, the MethodInfo that represents that method is the implementing method.Otherwise, 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 Boolean:

`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 Boolean.

If the implementing method is `null`

:

## Equal(Expression, Expression, Boolean, MethodInfo)

Creates a BinaryExpression that represents an equality comparison. The implementing method can be specified.

```
public:
static System::Linq::Expressions::BinaryExpression ^ Equal(System::Linq::Expressions::Expression ^ left, System::Linq::Expressions::Expression ^ right, bool liftToNull, System::Reflection::MethodInfo ^ method);
```

`public static System.Linq.Expressions.BinaryExpression Equal (System.Linq.Expressions.Expression left, System.Linq.Expressions.Expression right, bool liftToNull, System.Reflection.MethodInfo method);`

`static member Equal : System.Linq.Expressions.Expression * System.Linq.Expressions.Expression * bool * System.Reflection.MethodInfo -> System.Linq.Expressions.BinaryExpression`

`Public Shared Function Equal (left As Expression, right As Expression, liftToNull As Boolean, method As MethodInfo) As BinaryExpression`

#### Parameters

- left
- Expression

An Expression to set the Left property equal to.

- right
- Expression

An Expression to set the Right property equal to.

- liftToNull
- Boolean

`true`

to set IsLiftedToNull to `true`

; `false`

to set IsLiftedToNull to `false`

.

- method
- MethodInfo

A MethodInfo to set the Method property equal to.

#### Returns

A BinaryExpression that has the NodeType property equal to Equal and the Left, Right, IsLiftedToNull, and Method properties set to the specified values.

#### Exceptions

`left`

or `right`

is `null`

.

`method`

is not `null`

and the method it represents returns `void`

, is not `static`

(`Shared`

in Visual Basic), or does not take exactly two arguments.

`method`

is `null`

and the equality operator is not defined for `left`

.Type and `right`

.Type.

### Remarks

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 property is `true`

and the IsLiftedToNull property is equal to `liftToNull`

. Otherwise, they are both `false`

. 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

`method`

is not`null`

and it represents a non-void,`static`

(`Shared`

in Visual Basic) method that takes two arguments, it is the implementing method.Otherwise, if the Type property of either

`left`

or`right`

represents a user-defined type that overloads the equality operator, the MethodInfo that represents that method is the implementing method.Otherwise, 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; also, the type of the node is nullable Boolean if

`liftToNull`

is`true`

or Boolean if`liftToNull`

is`false`

:`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 Boolean.

If the implementing method is `null`

: