PHP switch Statement

Veröffentlicht 2024-05-17 07:47:56

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The switch statement is used to perform different actions based on different conditions.

The PHP switch Statement

Use the switch statement to select one of many blocks of code to be executed.

Syntax

switch (expression) {
  case label1:
    //code block
    break;
  case label2:
    //code block;
    break;
  case label3:
    //code block
    break;
  default:
    //code block
}

This is how it works:

The expression is evaluated once
The value of the expression is compared with the values of each case
If there is a match, the associated block of code is executed
The break keyword breaks out of the switch block
The default code block is executed if there is no match

ExampleGet your own PHP Server

$favcolor = "red";

switch ($favcolor) {
  case "red":
    echo "Your favorite color is red!";
    break;
  case "blue":
    echo "Your favorite color is blue!";
    break;
  case "green":
    echo "Your favorite color is green!";
    break;
  default:
    echo "Your favorite color is neither red, blue, nor green!";
}

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The break Keyword

When PHP reaches a break keyword, it breaks out of the switch block.

This will stop the execution of more code, and no more cases are tested.

The last block does not need a break, the block breaks (ends) there anyway.

Warning: If you omit the break statement in a case that is not the last, and that case gets a match, the next case will also be executed even if the evaluation does not match the case!

Example

What happens if we remove the break statement from case "red"?

$favcolor is red, so the code block from case "red" is executed, but since it has no break statement, the code block from case "blue" will also be executed:

$favcolor = "red";

switch ($favcolor) {
  case "red":
    echo "Your favorite color is red!";
  case "blue":
    "Your favorite color is blue!";
    break;
  case "green":
    echo "Your favorite color is green!";
    break;
  default:
    echo "Your favorite color is neither red, blue, nor green!";
}

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The default Keyword

The default keyword specifies the code to run if there is no case match:

Example

If no cases get a match, the default block is executed:

$d = 4;

switch ($d) {
  case 6:
    echo "Today is Saturday";
    break;
  case 0:
    echo "Today is Sunday";
    break;
  default:
    echo "Looking forward to the Weekend";
}

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The default case does not have to be the last case in a switch block:

Example

Putting the default block elsewhere than at the end of the switch block is allowed, but not recommended.

$d = 4;

switch ($d) {
  default:
    echo "Looking forward to the Weekend";
    break;
  case 6:
    echo "Today is Saturday";
    break;
  case 0:
    echo "Today is Sunday";
}

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Note: If default is not the last block in the switch block, remember to end the default block with a break statement.

Common Code Blocks

If you want multiple cases to use the same code block, you can specify the cases like this:

Example

More than one case for each code block:

$d = 3;

switch ($d) {
  case 1:
  case 2:
  case 3:
  case 4:
  case 5:  
    echo "The weeks feels so long!";
    break;
  case 6:
  case 0:
    echo "Weekends are the best!";
    break;
  default:
    echo "Something went wrong";
}