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    switch

    (PHP 4, PHP 5, PHP 7, PHP 8)

    The switch statement is similar to a series of IF statements on the same expression. In many occasions, you may want to compare the same variable (or expression) with many different values, and execute a different piece of code depending on which value it equals to. This is exactly what the switch statement is for.

    Note: Note that unlike some other languages, the continue statement applies to switch and acts similar to break. If you have a switch inside a loop and wish to continue to the next iteration of the outer loop, use continue 2.

    Note:

    Note that switch/case does loose comparison.

    The following two examples are two different ways to write the same thing, one using a series of if and elseif statements, and the other using the switch statement:

    Example #1 switch structure

    <?php
    if ($i == 0) {
        echo     "i equals 0";
    } elseif (    $i == 1) {
        echo     "i equals 1";
    } elseif (    $i == 2) {
        echo     "i equals 2";
    }

    switch (    $i) {
        case     0:
            echo     "i equals 0";
            break;
        case     1:
            echo     "i equals 1";
            break;
        case     2:
            echo     "i equals 2";
            break;
    }
    ?>

    Example #2 switch structure allows usage of strings

    <?php
    switch ($i) {
        case     "apple":
            echo     "i is apple";
            break;
        case     "bar":
            echo     "i is bar";
            break;
        case     "cake":
            echo     "i is cake";
            break;
    }
    ?>

    It is important to understand how the switch statement is executed in order to avoid mistakes. The switch statement executes line by line (actually, statement by statement). In the beginning, no code is executed. Only when a case statement is found whose expression evaluates to a value that matches the value of the switch expression does PHP begin to execute the statements. PHP continues to execute the statements until the end of the switch block, or the first time it sees a break statement. If you don't write a break statement at the end of a case's statement list, PHP will go on executing the statements of the following case. For example:

    <?php
    switch ($i) {
        case     0:
            echo     "i equals 0";
        case     1:
            echo     "i equals 1";
        case     2:
            echo     "i equals 2";
    }
    ?>

    Here, if $i is equal to 0, PHP would execute all of the echo statements! If $i is equal to 1, PHP would execute the last two echo statements. You would get the expected behavior ('i equals 2' would be displayed) only if $i is equal to 2. Thus, it is important not to forget break statements (even though you may want to avoid supplying them on purpose under certain circumstances).

    In a switch statement, the condition is evaluated only once and the result is compared to each case statement. In an elseif statement, the condition is evaluated again. If your condition is more complicated than a simple compare and/or is in a tight loop, a switch may be faster.

    The statement list for a case can also be empty, which simply passes control into the statement list for the next case.

    <?php
    switch ($i) {
        case     0:
        case     1:
        case     2:
            echo     "i is less than 3 but not negative";
            break;
        case     3:
            echo     "i is 3";
    }
    ?>

    A special case is the default case. This case matches anything that wasn't matched by the other cases. For example:

    <?php
    switch ($i) {
        case     0:
            echo     "i equals 0";
            break;
        case     1:
            echo     "i equals 1";
            break;
        case     2:
            echo     "i equals 2";
            break;
        default:
           echo     "i is not equal to 0, 1 or 2";
    }
    ?>

    Note: Multiple default cases will raise a E_COMPILE_ERROR error.

    The alternative syntax for control structures is supported with switches. For more information, see Alternative syntax for control structures.

    <?php
    switch ($i):
        case     0:
            echo     "i equals 0";
            break;
        case     1:
            echo     "i equals 1";
            break;
        case     2:
            echo     "i equals 2";
            break;
        default:
            echo     "i is not equal to 0, 1 or 2";
    endswitch;
    ?>

    It's possible to use a semicolon instead of a colon after a case like:

    <?php
    switch($beer)
    {
        case     'tuborg';
        case     'carlsberg';
        case     'heineken';
            echo     'Good choice';
            break;
        default;
            echo     'Please make a new selection...';
            break;
    }
    ?>

    add a note add a note

    User Contributed Notes 40 notes

    up
    256
    MaxTheDragon at home dot nl
    9 years ago
    This is listed in the documentation above, but it's a bit tucked away between the paragraphs. The difference between a series of if statements and the switch statement is that the expression you're comparing with, is evaluated only once in a switch statement. I think this fact needs a little bit more attention, so here's an example:

    <?php
    $a     = 0;

    if(++    $a == 3) echo 3;
    elseif(++    $a == 2) echo 2;
    elseif(++    $a == 1) echo 1;
    else echo     "No match!";

    // Outputs: 2

    $a = 0;

    switch(++    $a) {
        case     3: echo 3; break;
        case     2: echo 2; break;
        case     1: echo 1; break;
        default: echo     "No match!"; break;
    }

    // Outputs: 1
    ?>

    It is therefore perfectly safe to do:

    <?php
    switch(winNobelPrizeStartingFromBirth()) {
    case     "peace": echo "You won the Nobel Peace Prize!"; break;
    case     "physics": echo "You won the Nobel Prize in Physics!"; break;
    case     "chemistry": echo "You won the Nobel Prize in Chemistry!"; break;
    case     "medicine": echo "You won the Nobel Prize in Medicine!"; break;
    case     "literature": echo "You won the Nobel Prize in Literature!"; break;
    default: echo     "You bought a rusty iron medal from a shady guy who insists it's a Nobel Prize..."; break;
    }
    ?>

    without having to worry about the function being re-evaluated for every case. There's no need to preemptively save the result in a variable either.
    up
    77
    septerrianin at mail dot ru
    3 years ago
    php 7.2.8.
    The answer to the eternal question " what is faster?":
    1 000 000 000 iterations.

    <?php
    $s     = time();
    for (    $i = 0; $i < 1000000000; ++$i) {
          $x = $i%10;
      if (    $x == 1) {
            $y = $x * 1;
      } elseif (    $x == 2) {
            $y = $x * 2;
      } elseif (    $x == 3) {
            $y = $x * 3;
      } elseif (    $x == 4) {
            $y = $x * 4;
      } elseif (    $x == 5) {
            $y = $x * 5;
      } elseif (    $x == 6) {
            $y = $x * 6;
      } elseif (    $x == 7) {
            $y = $x * 7;
      } elseif (    $x == 8) {
            $y = $x * 8;
      } elseif (    $x == 9) {
            $y = $x * 9;
      } else {
            $y = $x * 10;
      }
    }
    print(    "if: ".(time() - $s)."sec\n");

    $s = time();
    for (    $i = 0; $i < 1000000000; ++$i) {
          $x = $i%10;
      switch (    $x) {
      case     1:
            $y = $x * 1;
        break;
      case     2:
            $y = $x * 2;
        break;
      case     3:
            $y = $x * 3;
        break;
      case     4:
            $y = $x * 4;
        break;
      case     5:
            $y = $x * 5;
        break;
      case     6:
            $y = $x * 6;
        break;
      case     7:
            $y = $x * 7;
        break;
      case     8:
            $y = $x * 8;
        break;
      case     9:
            $y = $x * 9;
        break;
      default:
            $y = $x * 10;
      }
    }
    print(    "switch: ".(time() - $s)."sec\n");
    ?>

    Results:
    if: 69sec
    switch: 42sec
    up
    88
    nospam at please dot com
    20 years ago
    Just a trick I have picked up:

    If you need to evaluate several variables to find the first one with an actual value, TRUE for instance. You can do it this was.

    There is probably a better way but it has worked out well for me.

    switch (true) {

      case (X != 1):

      case (Y != 1):

      default:
    }
    up
    48
    mmxg at shaw dot ca
    13 years ago
    In reply to lko at netuse dot de

    Just so others know whom may not, that's because PHP does automatic type conversion if a string is evaluated as an integer (it sees the 2 in '2string' so when compared like if ('2string' == 2), PHP sees if (2 == 2) ).

    I just tested it, but if you go:

    <?php

    $string    ="2string";

    switch(    $string)
    {
        case (string)     1:
            echo     "this is 1";
            break;
        case (string)     2:
            echo     "this is 2";
            break;
        case     '2string':
            echo     "this is a string";
            break;
    }

    ?>

    The output will be "this is a string" and if you change $string to "2" it will again be "this is 2".

    Just in case that may help anyone who may run into that problem.
    up
    46
    lko at netuse dot de
    13 years ago
    Attention if you have mixed types of value in one switch statemet it can make you some trouble

    <?php

    $string    ="2string";

    switch(    $string)
    {
        case     1:
            echo     "this is 1";
            break;
        case     2:
            echo     "this is 2";
            break;
        case     '2string':
            echo     "this is a string";
            break;
    }

    ?>

    The swich-statement will halt on 'case 2'

    Answer: this is 2
    up
    6
    sergey at neskhodovskiy dot com
    1 year ago
    As the doc states, switch uses loose comparison by default. We use the inversion trick (mentioned by many posters) to make it perform a strict one:

    $a = 0;

    switch (true) {
        case ($a === true):
            echo '$a is true';
            break;
        case ($a === false):
            echo '$a is false';
            break;
        case ($a === 0):
            echo '$a is 0';
            break;
    }

    // outputs correctly '$a is 0';
    up
    16
    manicdepressive at mindless dot com
    17 years ago
    Be careful if distinguishing between NULL and (int)0.  As implied in the above documentation, the case statements are equivalent to the '==' operator, not the '===' operator, so the following code did not work as i expected:

    <?php
    $mixed     = 0;
    switch(    $mixed){
       case     NULL: echo "NULL";  break;
       case     0: echo "zero";  break;
       default: echo     "other"; break;
    }
    ?>

    Instead, I may use a chain of else-ifs.  (On this page, kriek at jonkreik dot com states that "in most cases [a switch statement] is 15% faster [than an else-if chain]" but jemore at m6net dotdot fr claims that when using ===, if/elseif/elseif can be 2 times faster than a switch().)

    Alternatively, if i prefer the appearance of the switch() statement I may use a trick like the one nospam at please dot com presents:

    <?php
    $mixed     = 0;
    switch(    TRUE){
       case (    NULL===$mixed): //blah break;
           case (0   ===$mixed): //etc. break;
    }
    ?>

    code till dawn! mark meves!
    up
    11
    havar at henriksen dot nu
    18 years ago
    Remember, that you also could use functions in a switch.
    For example, if you need to use regular expressions in a switch:

    <?php
    $browserName     = 'mozilla';
    switch (    $browserName) {
      case     'opera':
        echo     'opera';
      break;
      case (    preg_match("/Mozilla( Firebird)?|phoenix/i", $browserName)?$browserName:!$browserName):
        echo     "Mozilla or Mozilla Firebird";
      break;
      case     'konqueror':
        echo     'Konqueror';
      break;
      default:
        echo     'Default';
      break;
    }
    ?>

    or you could just use a regular expression for everything:

    <?php
    $uri     = 'http://www.example.com';
    switch (    true) {
      case     preg_match("/$http(s)?/i", $uri, $matches):
        echo     $uri . ' is an http/https uri...';
      break;
      case     preg_match("/$ftp(s)?/i", $uri, $matches):
        echo     $uri . ' is an ftp/ftps uri...';
      break;
      default:
        echo     'default';
      break;
    }
    ?>
    up
    14
    Hayley Watson
    13 years ago
    Something not mentioned in the documentation itself, and only touched on momentarily in these notes, is that the default: case need not be the last clause in the switch.
    <?php
    for($i=0; $i<8; ++$i)
    {
        echo     $i,"\t";
        switch(    $i)
        {
        case     1: echo "One"; break;
        case     2:
        default: echo     "Thingy"; break;
        case     3:
        case     4: echo "Three or Four"; break;
        case     5: echo "Five"; break;
        }
        echo     "\n";
    }
    ?>
    Outputs what you'd expect, namely
    0       Thingy
    1       One
    2       Thingy
    3       Three or Four
    4       Three or Four
    5       Five
    6       Thingy
    7       Thingy
    with case 2 and the default both producing the same result ("Thingy"); strictly speaking, the case 2 clause is completely empty and control just falls straight through. The same result could have been achieved with
    <?php
    switch($i)
    {
        case     1: echo "One"; break;
        case     3:
        case     4: echo "Three or Four"; break;
        case     5: echo "Five"; break;
        default: echo     "Thingy"; break;
    }
    ?>
    But if "case 2" represented a fairly common case (other than "everything else"), then it would be better to declare it explicitly, not only because it saves time by not having to test EVERY other case first  (in the current example, PHP finds 'case 2' in the first switch in two tests, but in the second switch it has to make four tests before giving up and going with the default) but also because someone (perhaps yourself in a few months' time) will be reading the code and expecting to see it handled. Listing it explicitly aids comprehension
    up
    3
    none at example dot com
    2 years ago
    A note on continue, continue 2, and break:

    $a = [1, 2, 3];

    foreach($a as $b) {
      switch($b) {
        case 1:
          echo 'a'; continue;
        case 2:
          echo 'b'; continue;
        default:
          echo 'c'; continue;
      }

      echo '0';
    }
    // outputs a0b0c0 (and warns twice about continue in a switch statement)

    foreach($a as $b) {
      switch($b) {
        case 1:
          echo 'a'; break;
        case 2:
          echo 'b'; break;
        default:
          echo 'c'; break;
      }

      echo '0';
    }
    // outputs a0b0c0

    foreach($a as $b) {
      switch($b) {
        case 1:
          echo 'a'; continue 2;
        case 2:
          echo 'b'; continue 2;
        default:
          echo 'c'; continue 2;
      }

      echo '0';
    }
    //outputs abc0

    In short, continue and break will more or less behave the same (albeit the former throws out warnings), but continue 2 will end the loop iteration, and move to the next iteration (even if there is a block in the iteration after the switch statement).
    up
    8
    lchanady at gmail dot com
    11 years ago
    Something fairly simple (and maybe obvious) that I didn't see mentioned is that the default case WILL be executed even if the switched variable does not exist or is undefined.

    For example:

    <?php

    $a     = "abc";
    $b = "def";

    switch(    $c){
        case     "a":
            echo     "a";
            break;
        case     "b":
            echo     "b";
            break;
        default:
            echo     "default";
            break;
    }

    ?>

    Will output: default

    Even though $c was never declared or defined, the default case will still be executed rather than PHP throwing an error.
    up
    6
    richard
    12 years ago
    Just a word of warning about using switch don't try and compare variables that contain numbers with strings like so:

    <?php
    $i    =0;

    switch(    $i)
    {
        case     'TEST': print "Test";break;
        case     0: print "0";break;
    }
    ?>

    The output will be: Test and not 0.
    up
    4
    Anonymous
    6 years ago
    Please note that PHP won't throw any error/warning if your `switch` utilizes more than one `default` - in such case it will just jump to the first one.

    Also note that you (for unknown reason for me) are allowed to use semicolons `;` along colon `:` for `case` and `default` entries:

    <?php

    switch($foo) {
       case     0:    // colon
                ...
       break;

       case     1;    // semicolon is fine
                ...
       break;
    }
    up
    1
    mparsa1372 at gmail dot com
    7 months ago
    This is how it works: First we have a single expression n (most often a variable), that is evaluated once. The value of the expression is then compared with the values for each case in the structure. If there is a match, the block of code associated with that case is executed. Use break to prevent the code from running into the next case automatically. The default statement is used if no match is found.

    <?php
    $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!";
    }
    ?>
    up
    0
    willie dot owens91 at gmail dot com
    6 months ago
    I'm not sure expressions in case statements are even document (don't see it here), but watch out for this:

    ```
    function switchTest($integerValue) {
        switch ($integerValue) {
        case ($integerValue > 10):
            return 'big';
        default:
            return 'small';
        }
    }
    ```

    switchTest(0) will return 'big'...

    I'm really not sure why.
    up
    -1
    brentmmonson at gmail dot com
    1 year ago
    You can use multiple break statements within a case. In this contrived example, I get out of the first case of the switch statement once a condition is met. Just remember to include another break statement as a failsafe.

    <?php

    $disk     = '3.5 inch floppy';

    switch (    $disk) {
        case     '5 inch floppy':
        case     '3.5 inch floppy':
        case     'usb':
        case     'cd':
       
            echo     "Reading disk...";
       
            if (    strpos($disk, 'floppy') !== false) {
                echo     "It bent.";
                break;
            }
           
            echo     "It worked.";
            break;     // failsafe
       
            default:
            echo     "Don't stick cupcakes in here.";
            break;
    }
    up
    0
    Manucyan
    2 years ago
    Some tests:

    switch ('aaaaa') {
            default         : echo "DEFAULT TOP 1"; break;
            default         : echo "DEFAULT TOP 2"; break;
           
            case 'aaaaa': echo "CASE TOP 1"; break;
            case 'aaaaa': echo "CASE TOP 2"; break;
           
            default         : echo "DEFAULT BOTTOM 1"; break;
            default         : echo "DEFAULT BOTTOM 2"; break;
           
            case 'aaaaa': echo "CASE BOTTOM 1"; break;
            case 'aaaaa': echo "CASE BOTTOM 2"; break;
    }
    //return ------>  CASE TOP 1

    switch ('SOMETHING_THAT_DOESN_T_EXIST') {
            default         : echo "DEFAULT TOP 1"; break;
            default         : echo "DEFAULT TOP 2"; break;
           
            case 'aaaaa': echo "CASE TOP 1"; break;
            case 'aaaaa': echo "CASE TOP 2"; break;
           
            default         : echo "DEFAULT BOTTOM 1"; break;
            default         : echo "DEFAULT BOTTOM 2"; break;
           
            case 'aaaaa': echo "CASE BOTTOM 1"; break;
            case 'aaaaa': echo "CASE BOTTOM 2"; break;
    }
    //return ------>  DEFAULT BOTTOM 2

        Some observations:
        - no errors if several identical boxes or defaultes
        - the last defect takes over
        - the first of the boxes takes the hand
        - we can put the default at the top (indeed sometimes it's more intuitive)
    up
    2
    Anonymous
    9 years ago
    Rewriting the function (to be three times faster) provided by [stever at ashomecare dot com 07-Sep-2007 09:11] and demonstrating points that others have made:

    <?php
    function getChineseZodiac($year){

        switch (    $year % 12) :
            case      0: return 'Monkey';  // Years 0, 12, 1200, 2004...
                case  1: return 'Rooster';
            case      2: return 'Dog';
            case      3: return 'Boar';
            case      4: return 'Rat';
            case      5: return 'Ox';
            case      6: return 'Tiger';
            case      7: return 'Rabit';
            case      8: return 'Dragon';
            case      9: return 'Snake';
            case     10: return 'Horse';
            case     11: return 'Lamb';
        endswitch;
    }

    echo     getChineseZodiac(2016);
    ?>
    up
    1
    chernyshevsky at hotmail dot com
    19 years ago
    Be very careful when you're using text strings as cases. If the variable supplied to switch() is an integer, the cases would be converted to integer before the comparison is made (usually to zero). The following snippet prints "hello".

    <?php
    $a     = 0;
    switch(    $a) {
    case     'Hello': echo "Hello";
    break;
    }
    ?>
    up
    0
    druellan at sfidastudios dot com
    7 years ago
    Be careful if you have mixed types of values in the switch statement. Explicitly cast your variables where possible to avoid mismatch:

    <?php
    $var     = 0;

    // This match case #1
    // switch ( $var )

    // This works as expected
    switch ( (string)$var )
    {
      case     "0string":
        echo     "0string match";
        break;
    }
    ?>
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    0
    theimp at iinet dot net dot au
    11 years ago
    It's easy to abuse the switch syntax to do some very useful things. As this example will show, the possibilities can go beyond even Duff's Device-style craziness (not that this example is nearly as clever as Duff's Device, but it demonstrates how you can do certain things other than simply the increment/decrement/assignment that's possible in C).

    Fundamentally, this works mostly due to the fact that, from the point of view of the assembler/interpreter, a switch block is hardly any different from a bunch of GOTO labels and  if()  evaluations. But, like an  if() evaluation, the line of a case: statement is evaluated as an expression. So, in this case, we can perform an assignment and match the result of that assignment, because the return value of an assignment is the data that was assigned (and not the value of the variable it was assigned to, as you might expect).

    So far, this is not actually amazing, even if it is a bit unintuitive. From a language point-of-view, it would be the same as an  if($var = "string")  statement which is using an assignment (=) rather than a comparison (==) operator. When you look at the pre-processing optimization, because a normal assignment of $var = "string" will always equal "string", it makes sense to have the result of that expression simply be equal to the right side of the expression (the right side is used rather than the left to let the assembler/interpreter work faster, on account of how they traditionally simply change the memory location for the assigned variable rather than copy the memory around unnecessarily).

    Where this becomes more interesting is where, in PHP, you have language constructs that behave like functions but are used like statements. An  $array[] = "string"  expression is actually a language construct that just happens to behave a lot like a function, but you use it in the same way that you use an assignment expression, and like an expression, it always evaluates to the right side of the expression; in this case,  "string"  and not  array() .

    The assembler/interpreter can't use the right side of the expression as a shortcut for the result of a function, so you can't use functions in this way in a case statement. You also can't get around this limit on calling functions from the case line by using variable functions, because they are used in the same way as functions.

    But imagine what you could do with other language constructs, like eval() or include() !

    Consider the following:

    <?php
    function flavor($type = null)
    {
        switch (    $type) {
                /* Note the isolation of break; statements and the fact that default: is at the top */
                default:
                    $type = null;
            case     $array[] = "chocolate":
                if (    $type != null) {
                        $array = array($type);
                    break;
                }
            case     $array[] = "strawberry":
                if (    $type != null) {
                        $array = array($type);
                    break;
                }
            case     $array[] = "vanilla":
                if (    $type != null) {
                        $array = array($type);
                    break;
                }
        }
        if ( (    count($array) != 1) ) {
            return     "Flavors available: " . implode(", ", $array);
        } else {
            return     "Flavor selected: " . implode(", ", $array);
        }
    }

    echo     flavor() . "<br>";
    /* Flavors available: chocolate, strawberry, vanilla */

    echo flavor("banana") . "<br>";
    /* Flavors available: chocolate, strawberry, vanilla */

    echo flavor("chocolate") . "<br>";
    /* Flavor selected: chocolate */
    ?>

    What makes this example useful is that you don't need a variable somewhere that contains the available options (even within the function itself), so to support new options, you only ever have to change the code to add the new option - you don't need to update some variable somewhere that controls whether or not it works or whether or not people can tell that there's a new option.
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    0
    shawn at evilest dot net
    18 years ago
    You can also nest switch statements inside case statements:

    <?php
           // Set argument handlers
            $argv = explode(",", urldecode(getenv('QUERY_STRING')));
            $argc = array_shift($argv);
            $argd = array_shift($argv);
            $arge = array_shift($argv);
    ?>

       // Begin switching

    <?php
            switch ($argc) {
            case     'home': {
                 print(    'This is $argc, home case.');
                break;
            }
            case     'subsection': {
                    switch (    $argd) {
                         case     'links': {
                                switch(    $arge) {
                                    case     'display': {
                                    print(    'This is $arge, subsection,links,display case.');
                                    break;
                                    }
                               }
                        }
                    }
            }
        }
    ?>
    up
    -1
    Keil
    12 years ago
    As follow-up to ben dot lancaster at holler dot co dot uk's post:

    'continue' ends the switch, not the case, just as it would with any other flow control. Think of it as putting the execution pointer right before the ending accolade (that is, the }) because that is essentially what happens. In the case of a for loop, this would cause the iteration clause to execute, and if applicable, the loop to begin again. However, switches do not loop, which is why (as noted above, in the manual!) a continue statement essentially acts as a break when within a switch.
    up
    -3
    sedativchunk at gmail dot com
    12 years ago
    Not sure if this has been posted or not, but I found the switch statement useful for finding ranges of data.

    This script creates web 2.0 style links in different font sizes (popular on blogs) using a randomizer and switch statement. I used links from within a database for a mod I made for a Simple Machines forums, but this example uses arrays for links if you wanted to add your own custom links:
    <?php
    // Create set of links
    $link = array();
    $link[] = '<a href="whatever.html">page 1</a>';
    $link[] = '<a href="whatever.html">page 2</a>';
    $link[] = '<a href="whatever.html">page 3</a>';
    $link[] = '<a href="whatever.html">page 4</a>';
    $link[] = '<a href="whatever.html">page 5</a>';
    $link[] = '<a href="whatever.html">page 6</a>';
    $link[] = '<a href="whatever.html">page 7</a>';
    $link[] = '<a href="whatever.html">page 8</a>';

    // Create loop to display links
    for($i = 0; $i < count($link); ++$i)
    {
            // Create randomizer
        // Use switch statement to find font size
            $randomizer = rand(1,50);
        switch(    $randomizer)
        {
        case (    $randomizer <= 20):
            $font_size = "11";
        break;

        case (    $randomizer <= 30):
            $font_size = "16";
        break;

        case (    $randomizer <= 40):
            $font_size = "18";
        break;

        case (    $randomizer <= 50):
            $font_size = "20";
        break;
        }

            // Display the link
            echo '<span style="font-size: ' .$font_size. ';">' .$link[$i]. '</span>&nbsp;&nbsp;';

    // Loop the next link
    }
    ?>

    Using this type of range randomizer is useful for game development and it can be useful on the web too, for things where you don't want to use a randomizer just for things like (1-5) where you wanted a more then likely result for one thing over another. The switch statement saves from writing spaghetti code if statements.
    up
    -1
    paz at spiralon dot com
    19 years ago
    In case : ) it helps someone, I was able to clean up some hairball code by using nested switches (didn't see it mentioned here).  Thanks to all those who are writing examples - I love this site!

    <?php
    $string_match    ="second";
    switch (    $string_match) {
    case     "first":
    case     "second":
    case     "third":
        print     "<H3>Something for all three</H3><br>";
        switch (    $string_match) {
          case     "first":
          print     "something for first only";
          break;
          case     "second":
          case     "third":
          print     "something for the other two";
          break;
        }
    break;
    default:
    print     "<H3>no match</H3>";
    }
    ?>
    up
    -3
    mar dot czapla at gmail dot com
    13 years ago
    <?php
            /* script 1  */
            $foo = "not a number";
        switch(    false)
        {
            case     "1":    {    $foo = "1";    break;    }
            case     "2":    {    $foo = "2";    break;    }
            default:    {        $foo = "0";    }
        }
       
        echo     $foo;    // will produce "not a number"
       
        /* script 2  */
            $foo = "not a number";
            $arr = array("not a number"); // 1 element only !
            switch($arr[1])    // element $foo[1] doesn't defined
            {
            case     "1":    {    $foo = "1";    break;    }
            case     "2":    {    $foo = "2";    break;    }
            default:    {        $foo = "0";    }
        }
       
        echo     $foo;    // will produce "not a number" ( not 0 ! )
       
        /* script 3  */
            $foo = "not a number";
            $arr = array("not a number"); // 1 element only !
            switch($arr[1]?$arr[1]:"1")    // element $foo[1] doesn't defined
            {
            case     "1":    {    $foo = "1";    break;    }
            case     "2":    {    $foo = "2";    break;    }
            default:    {        $foo = "0";    }
        }
       
        echo     $foo;   
            // will produce :
        // 1 if $arr[1] isn't set
        // 1 if $arr[1]=1
        // 2 if $arr[1]=2
        // 0 if none of above
    ?>
    up
    -3
    info at maisuma dot jp
    6 years ago
    If you want to avoid numeric compare for numeric strings in switch statement, try prepending something non-numeric.

    e.g.
    <?php
    $val    ='2';
    switch(    $val){
    case     '2.0' : echo '2.0!??'; break;
    case     '2' : echo '2.'; break;
    }
    ?>
    echoes '2.0!??' ; while prepended version
    <?php
    $val    ='2';
    switch(    '#' . $val){
    case     '#2.0' : echo '2.0!??'; break;
    case     '#2' : echo '2.'; break;
    }
    ?>
    echoes '2.'.
    up
    -4
    hamiltont at gmail dot com
    12 years ago
    Example of default NOT included as the last item

    <?php
    switch(5) {
      case     1:
        echo     "1";
        break;
      case     2:
      default:
        echo     "2, default";
        break;
      case     3;
        echo     "3";
        break;
    }
    ?>

    Outputs '2,default'

    very useful if you want your cases to be presented in a logical order in the code (as in, not saying case 1, case 3, case 2/default) and your cases are very long so you do not want to repeat the entire case code at the bottom for the default

    Hamy
    up
    -2
    php dot net dot 1 at yogelements dot com
    17 years ago
    Declaring a variable (actually an array) as static w/in a switch{} spun my wool for a while:
    don't:
    <?
    function ss() {
        switch ("bug") {
            case "bug" :
               static $test = "xyz";
               break;
            default :
               static $test = "abc";
        }
    echo $test;
    }
    ss(); //abc
    ?>
    do:
    <?
    function tt() {
        static $test;
        switch ("fix") {
            case "fix" :
               $test = "xyz";
               break;
            default :
               $test = "abc";
        }
    echo $test;
    }
    tt(); // xyz
    ?>
    up
    -3
    Anonymous
    9 years ago
    Regarding [php_net at mcdragonsoftware dot com 17-Jun-2011 09:53]; the elegant function and syntax provided for an "inline switch" statement is more readable and about 25% faster than this alternative (that uses existing builtin functions), which produces the same result:

    <?php echo array_pop(array_slice(array( 'rock', 'paper', 'scissors' ), --$roll, 1)); ?>
    up
    -4
    cretz
    13 years ago
    Haven't seen it mentioned here, but at least in my version (PHP 5.2.5) and I'm sure all of PHP 5, the switch statement is a great way to check type safe enumerates that are otherwise missing in the PHP language. Example:

    <?php

    class WannabeEnum {
            /**
         * @var WannabeEnum
         */
            public static $FOO;
            /**
         * @var WannabeEnum
         */
            public static $BAR;
            /**
         * @var WannabeEnum
         */
            public static $FOOBAR;
        private     $_ordinal;
        public function     __construct($ordinal) {
                $this->_ordinal = $ordinal;
        }
    }
    WannabeEnum::$FOO = new WannabeEnum(1);
    WannabeEnum::$BAR = new WannabeEnum(2);
    WannabeEnum::$FOOBAR = new WannabeEnum(3);

    function     testSwitch(WannabeEnum $wannabeEnum) {
        switch(    $wannabeEnum) {
            case     WannabeEnum::$FOO:
                echo(    'Foo!' . PHP_EOL);
                break;
            case     WannabeEnum::$BAR:
                echo(    'Bar!' . PHP_EOL);
                break;
            default:
                echo(    'Default!' . PHP_EOL);
        }   
    }
    testSwitch(WannabeEnum::$FOO);
    testSwitch(WannabeEnum::$FOOBAR);
    ?>

    Outputs:

    Foo!
    Default!

    Don't forget it uses loose comparisons!
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    -3
    theonly dot mcseven at gmx dot net
    18 years ago
    working a bit around with it I found out that it is not possible to
    compare the variable with two different values in one step like this
    (system running a w2k server, apache2.0.43 & php430):

    <?php
    switch ($myvar) {
    case (    "foo" || "bar"): //do something
    break;
    case (    "other"): //do another thing
    break;
    default:
    }
    ?>

    rather use:

    <?php
    switch ($myvar) {
    case (    "foo"):
    case (    "bar"): //do something
    break;
    case (    "other"): //do another thing
    break;
    default:
    }
    ?>
    up
    -2
    x@x
    20 years ago
    often you will have to perform multiple actions in sequence, but this sequence must be broken once one of them detects a stop condition (such as an error, when validating form request variables).
    One way is to use:

    if (check1()
    && check2()
    && check3()
    ) valid();
    else error();

    But when the sequence is long and must reordered, this can be errorprone because not all line of check have the same syntax (imagine that you want to comment one of them).

    Another way is to rewrite it as:

    check1() and
    check2() and
    check3() and
    ...
    valid() or
    error();

    The above syntax does not fit well when the valid() code must be several statements.
    An alternative syntax can be:

    switch (false) {
    case check1():
    case check2():
    case check3():
      error();
      break;
    default:
      valid();
    }

    This last equivalent sample show you that each case expressions is evaluated, until one of them evaluates to a value equal (==) to the switch expression. Above, the error() code will only be called if one of the check evaluates to false. And the valid() code will only be evaluated only if the switch reach the default, which means that none of the above check returned false...
    up
    -2
    jon
    17 years ago
    In response to the entry by "kriek at jonkriek dot com", I think you would probably be better of doing this:
    <?php
            // ensure $_GET['go'] is set, an integer, and not 0
        // then, set nav number; default to 1
            $nav = ( isset($_GET['go']) && (intval($_GET['go']) == $_GET['go']) && $_GET['go'] ) ?
                intval($_GET['go']) : 1;

            // format navigation string and include
            include(sprintf("Page%02d.php",$nav));   
    ?>

    ... as oppposed to the switch setup you recommended, which is limited to the number of cases you specify...
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    -3
    rmunn at pobox dot com
    18 years ago
    In answer to njones at fredesign dot com, what you're seeing is the way the switch statement is supposed to work. The switch statement evaluates the cases, top to bottom, until it finds the first one that matches the value being switch()ed on. So, for example, if you had:

    <?php
    switch(2) {
    case     1: echo "One\n"; break;
    case     2: echo "Two\n"; break;
    case     3: echo "Three\n"; break;
    case     2: echo "Two again\n"; break;
    }
    ?>

    Only "Two" would get echoed. "Two again" would NOT get echoed, because once the first case matches, the rest of them do NOT get evaluated. As soon as a matching case is found, the statements starting at that case get executed until the first break, then control flows out the bottom of the switch block.
    up
    -5
    Anonymous
    9 years ago
    Switch usage for make some actions with all of cases

    <?php
    $out     = ' ';
    for (    $i=1;$i<10:$i++) {
       switch (    $i) {
          case     true: $out .= 'test_';
          case     1:
          case     2:
          case     3: $out .= $i;
          default:     $out .= ' ';
       }
    }
    echo     $out;
    ?>

    That sample out:

    " test_1 test_2 test_3 "
    up
    -8
    mr at bwsolution dot de
    11 years ago
    "loose comparison" means that switch won't check the type.
    switch will only compare values:
    <?php
    if('a string' == 0) echo 'a string is 0' . PHP_EOL;
    if(    'a string' === 0) echo 'but you will never see this' . PHP_EOL;
    switch(    0){
        case     'a string': echo 'a string' . PHP_EOL;
        case     'another string': echo 'another string' . PHP_EOL;
    }

    if(    'a string' == true) echo 'a string is TRUE' . PHP_EOL;
    if(    'a string' === true) echo 'but you will never see this' . PHP_EOL;
    switch(    true){
        case     'a string': echo 'a string' . PHP_EOL;
        case     'another string': echo 'another string' . PHP_EOL;
    }
    ?>

    will output:
    a string is 0
    a string
    another string
    a string is TRUE
    a string
    another string
    up
    -6
    gmgiles at pacbell dot net
    17 years ago
    Did you know that switch() and case() can also accomodate things like basic math calculations and counter incrementing? They do. In this example, I use a switch statement (which is inside of a while loop) to alternate the background color of a table row. It gives me a cool spool-printer-paper effect.

    <?php
    $rows_per_color     = 5;  // change bgcolor every 5 rows
    switch($ctr++) {
        case     0:
                $bgcolor = "#ffffff";
            break;
        case (    $rows_per_color):
                $bgcolor = "#ff0000";
            break;               
        case (    $rows_per_color * 2):
                $bgcolor = "#ffffff";
                $ctr = 1;
            break;       
    }
    ?>

    As you can see, I increment $ctr by 1 in the switch() itself, and the final case() does a simple calculation. Simple, but powerful. [Remember, the above example is inside of a while() loop... each time it iterates, switch increments $ctr.]
    up
    -6
    2mareks (at) gmail (dot) com
    14 years ago
    In reply to earlier comment, "switch"- I found this to be one of the best ways to interpret 'actions'. Simply create a new instance of Handler_action before including any content source files. This is a highly stripped version of the class.

    The real one I created handles (and secures) input for $_GET and $_POST, creates a 'permission' array that only allows certain actions to be called by non-admins, and creates handy little diagnostic messages that can be displayed upon redirecting.

    On that note, the beauty in this class really shines in the simple redirect. You wont be left with ugly URLs like, "http://www.domain.com/path/to/script.php?action=blah&var1=123". Rather, you will be left with something like "http://www.domain.com/path/to/script.php"- helps protect some of the site by not showing any vulnerabilities in URLs.

    Also, this class keeps all actions organized neatly by directly passing $_GET vars to the actions through function parameters.

    <?php
          class Handler_action {
        function     __construct( ){
              //Add code here to secure attacks through $_GET or use $_POST
              $action = $_GET["action"];
     
              //$actions_index conventions:
          //'action_name' => array( 'arg1', 'arg2', 'etc', ['/redirect/to/path' | NULL ] )
              $actions_index = array(
                'create' => array( $_GET['newVar1'], $_GET['newVar2'], '/home.php' ),
                'edit' => array( $_GET['id'], $_GET['otherVar'], '/home.php' ),
                'delete' => array( $_GET['id'], '/other_script.php' )
          );
                 
          if(     $action && array_key_exists( $action, $actions_index ) ){
                $redirect_path = array_pop( $actions_index[$action] );
                call_user_func_array( array( &$this, $action ), $actions_index[$action] );
            if(     $redirect_path )
                  header( "Location: http://www.domain.com{$redirect_path}" );
          }
        }

            //being defining actions now
            function create( $new_var1, $new_var2 ){
     
              //code...
     
            }
        function     edit( $id, $other_var ){
     
              //code...
     
            }
        function     delete( $id ){
     
              //code...
     
            }
      }
    ?>
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    -14
    Anonymous
    14 years ago
    I could have used a swich for this, but I found that using the array was much faster.

        $action = $_GET['action'];

        $pages = array
        (
          'edit'   => './edit.php',
          'search' => './search.php'
        );

        if(strlen($pages[$action]) > 0)
        {
          require $pages[$action];
        }
        else
        {
          require './default.php';
        }
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