The meaning of default in c language

default represents the code block executed by default in the switch statement of C language, which is used to handle the situation where no case label is matched. Its syntax is: default: {code block}. The default code block provides a mechanism for handling cases that are not explicitly handled. If the value of expression does not match any case label, the default code block is executed.

The meaning of default in C language

default is a reserved keyword in C language, used in A switch statement represents a block of code that is executed by default. It is usually placed at the end of a switch statement to handle cases where no case labels match.

Syntax

<code class="c">switch (expression) {
  case value1:
    // 代码块
    break;
  case value2:
    // 代码块
    break;
  ...
  default:
    // 默认代码块
    break;
}</code>

Function

• The default code block provides support for the switch statement that is not explicitly processed. mechanism for handling the situation.
• If the value of expression does not match any case label, the default code block is executed.
• default code block may not contain a break statement, which will cause the program to continue executing the statement after the switch statement.

Example

The following example shows the usage of default:

<code class="c">switch (choice) {
  case 1:
    printf("你选择了选项 1\n");
    break;
  case 2:
    printf("你选择了选项 2\n");
    break;
  default:
    printf("无效选项\n");
}</code>

If the value of choice is not 1 or 2, the default code is executed block and prints an "invalid option" message.

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