介绍

switch 语句可用于创建分支逻辑，每个语句都具有基于可读性和维护性的独特优势。

学习目标

• 利用开关大小写结构将变量或表达式与多个潜在结果进行比较。

开发人员的先决条件

• 利用该构造来合并分支逻辑。if-else
• 处理变量，采用字符串插值，并显示输出。

开始

什么是 switch 语句？

switch 语句从称为 switch 部分的选项列表中选择并执行特定的代码部分。此选择是通过将开关表达式与开关部分中的预定义模式进行匹配来进行的。

基本示例

switch (fruit)  
{  
    case "apple":  
        Console.WriteLine($"App will display information for apple.");  
        break;  
  
    case "banana":  
        Console.WriteLine($"App will display information for banana.");  
        break;  
  
    case "cherry":  
        Console.WriteLine($"App will display information for cherry.");  
        break;  
}

基本开关示例

首先，在控制台应用程序中创建一个名为“”的静态类文件。将提供的代码片段插入到此文件中。Switch.cs

static int employeeLevel = 200;
static string employeeName = "John Smith";

/// <summary>
/// Outputs
/// John Smith, Senior Associate
/// </summary>
public static void SwitchExample()
{
    string title = "";

    switch (employeeLevel)
    {
        case 100:
            title = "Junior Associate";
            break;
        case 200:
            title = "Senior Associate";
            break;
        case 300:
            title = "Manager";
            break;
        case 400:
            title = "Senior Manager";
            break;
        default:
            title = "Associate";
            break;
    }

    Console.WriteLine($"{employeeName}, {title}");
}

从 main 方法执行代码，如下所示

#region Day 3 - Switch Constructs  
  
Switch.SwitchExample();  
  
#endregion

控制台输出

// Console Output  
John Smith, Senior Associate

更改开关标签

将另一个方法添加到同一个静态类中，如下所示

static int employeeLevel = 200;
static string employeeName = "John Smith";

public static void SwitchExample()
{
    string title = "";

    switch (employeeLevel)
    {
        case 100:
            title = "Junior Associate";
            break;
        case 200:
            title = "Senior Associate";
            break;
        case 300:
            title = "Manager";
            break;
        case 400:
            title = "Senior Manager";
            break;
        default:
            title = "Associate";
            break;
    }

    Console.WriteLine($"{employeeName}, {title}");
}

/// <summary>
/// John Smith, Associate
/// </summary>
public static void ChangeSwitchLabelExample()
{
    employeeLevel = 201;
    SwitchExample();
}

从 main 方法执行代码，如下所示

#region Day 3 - Switch Constructs  
  
Switch.ChangeSwitchLabelExample();  
  
#endregion

控制台输出

// Console Output  
John Smith, Associate

多个开关标签

将另一个方法添加到同一个静态类中，如下所示

/// <summary>
/// Outputs
/// John Smith, Senior Associate
/// </summary>
public static void MultipleSwitchLabelExample()
{
    int employeeLevel = 100;
    string employeeName = "John Smith";

    string title = "";

    switch (employeeLevel)
    {
        case 100:
        case 200:
            title = "Senior Associate";
            break;
        case 300:
            title = "Manager";
            break;
        case 400:
            title = "Senior Manager";
            break;
        default:
            title = "Associate";
            break;
    }

    Console.WriteLine($"{employeeName}, {title}");
}

从 main 方法执行代码，如下所示

#region Day 3 - Switch Constructs  
  
Switch.MultipleSwitchLabelExample();  
  
#endregion

控制台输出

// Console Output  
John Smith, Senior Associate

源代码获取：公众号回复消息【code：16914】