The PHP switch statement is a control structure used to perform different actions based on different conditions, providing an alternative to long if...elseif...else chains. It evaluates a single expression once and compares its value against multiple predefined case values.

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

Syntax for switch

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

Example:

$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!";
}

The PHP break Keyword

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

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

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

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!";
}

The PHP 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";
}

Combining Cases

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 week feels so long!";
    break;
  case 6:
  case 0:
    echo "Weekends are best!";
    break;
  default:
    echo "Something went wrong";
}