zoukankan      html  css  js  c++  java
  • switch statement

     

    switch statement allows a program to evaluate an expression and attempt to match the expression's value to a case label. If a match is found, the program executes the associated statement. A switch statement looks as follows:

    switch (expression) {
      case label_1:
        statements_1
        [break;]
      case label_2:
        statements_2
        [break;]
        ...
      default:
        statements_def
        [break;]
    }
    

      

    The program first looks for a case clause with a label matching the value of expression and then transfers control to that clause, executing the associated statements. If no matching label is found, the program looks for the optional default clause, and if found, transfers control to that clause, executing the associated statements. If no default clause is found, the program continues execution at the statement following the end of switch. By convention, the default clause is the last clause, but it does not need to be so.

    The optional break statement associated with each case clause ensures that the program breaks out of switch once the matched statement is executed and continues execution at the statement following switch. If break is omitted, the program continues execution at the next statement in the switch statement.

    Example

    In the following example, if fruittype evaluates to "Bananas", the program matches the value with case "Bananas" and executes the associated statement. When break is encountered, the program terminates switch and executes the statement followingswitch. If break were omitted, the statement for case "Cherries" would also be executed.

    switch (fruittype) {
      case "Oranges":
        console.log("Oranges are $0.59 a pound.");
        break;
      case "Apples":
        console.log("Apples are $0.32 a pound.");
        break;
      case "Bananas":
        console.log("Bananas are $0.48 a pound.");
        break;
      case "Cherries":
        console.log("Cherries are $3.00 a pound.");
        break;
      case "Mangoes":
        console.log("Mangoes are $0.56 a pound.");
        break;
      case "Papayas":
        console.log("Mangoes and papayas are $2.79 a pound.");
        break;
      default:
       console.log("Sorry, we are out of " + fruittype + ".");
    }
    console.log("Is there anything else you'd like?");
    

      

  • 相关阅读:
    Java NIO类库Selector机制解析(上)
    SWT Display.getDefault() 和Display.getCurrent()的区别
    VSS 2005 复位 工作目录(Reset Working Folder)
    转:理解javascript中的delete机制(2)
    在 .NET Framework 2.0 中未处理的异常导致基于 ASP.NET 的应用程序意外退出
    CSS样式
    Character Animator不显示NDI无法OBS直播
    【LoadRunner】基础使用教程:录制第一个脚本(包含遇到的错误问题解决)
    流式传输 之四流式协议
    全局变量,静态变量,局部变量
  • 原文地址:https://www.cnblogs.com/hephec/p/4601261.html
Copyright © 2011-2022 走看看