Avoid errors caused by default in C switch statements

A strategy to avoid errors caused by default in C switch statements: Use enums instead of constants, limiting the value of the case statement to a valid member of the enum. Use fallthrough in the last case statement and let the program continue to execute the following code. For switch statements without fallthrough, always add a default statement for error handling or provide default behavior.

Avoid errors caused by default in C language switch statements

In C, switch statements are used to execute different code blocks based on the value of an expression. If the value of the expression does not match any case statement, the default statement is executed.

A strategy to avoid default errors:

• Replace constants with enums:

  • Creates an enumeration type for the values ​​used in switch.
  • Limits the value of the case statement to a valid member of the enum.
  • By default, the compiler will generate a warning indicating that the default statement is missing.

• Using fallthrough:

  • Use fallthrough in the last case statement, indicating that if the last case matches the switch expression, continue to execute the following code.
  • However, in this case, the break statement is not recommended, as it causes the program to exit the switch block.

• Add default statement:

  • For switch statements without fallthrough, always add a default statement.
  • The default statement can perform error handling or provide default behavior without a match case.

Example:

 <code class="c">#include <stdio.h> enum Color { RED, GREEN, BLUE }; int main() { enum Color color = RED; switch (color) { case RED: printf("颜色是红色\n"); break; case GREEN: printf("颜色是绿色\n"); break; case BLUE: printf("颜色是蓝色\n"); // 在最后一个case 中使用fallthrough fallthrough; default: printf("颜色未知\n"); break; } return 0; }</stdio.h></code>

In the example above, enumerate the Color used for the values ​​in the switch statement. Use fallthrough to continue executing the default statement in case the color is an unknown color.

The above is the detailed content of Avoid errors caused by default in C switch statements. For more information, please follow other related articles on the PHP Chinese website!