ConstantExpression 类

定义

public ref class ConstantExpression : System::Linq::Expressions::Expression

public ref class ConstantExpression sealed : System::Linq::Expressions::Expression

public class ConstantExpression : System.Linq.Expressions.Expression

public sealed class ConstantExpression : System.Linq.Expressions.Expression

type ConstantExpression = class
    inherit Expression

Public Class ConstantExpression
Inherits Expression

Public NotInheritable Class ConstantExpression
Inherits Expression

继承

Object

Expression

ConstantExpression

示例

下面的代码示例演示如何使用 Constant 该方法创建表示常量值的表达式。

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

// This expression represents a Constant value.
Expression constantExpr = Expression.Constant(5.5);

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

// You can also use variables.
double num = 3.5;
constantExpr = Expression.Constant(num);
Console.WriteLine(constantExpr.ToString());

// This code example produces the following output:
//
// 5.5
// 3.5

' Add the following directive to your file:
' Imports System.Linq.Expressions 

' This expression represents a constant value.
Dim constantExpr As Expression = Expression.Constant(5.5)

' Print the expression.
Console.WriteLine(constantExpr.ToString())

' You can also use variables.
Dim num As Double = 3.5
constantExpr = Expression.Constant(num)
Console.WriteLine(constantExpr.ToString())

' This code example produces the following output:
'
' 5.5
' 3.5

注解

使用 Constant 工厂方法创建一个 ConstantExpression。

一 NodeType 个 ConstantExpression 是 Constant。