PHPerKaigi 2021

goto

(PHP 5 >= 5.3.0, PHP 7, PHP 8)

What's the worse thing that could happen if you use goto?
Image courtesy of » xkcd

The goto operator can be used to jump to another section in the program. The target point is specified by a case-sensitive label followed by a colon, and the instruction is given as goto followed by the desired target label. This is not a full unrestricted goto. The target label must be within the same file and context, meaning that you cannot jump out of a function or method, nor can you jump into one. You also cannot jump into any sort of loop or switch structure. You may jump out of these, and a common use is to use a goto in place of a multi-level break.

Example #1 goto example

<?php
goto a;
echo 
'Foo';
 
a:
echo 
'Bar';
?>

The above example will output:

Bar

Example #2 goto loop example

<?php
for($i=0,$j=50$i<100$i++) {
  while(
$j--) {
    if(
$j==17) goto end
  }  
}
echo 
"i = $i";
end:
echo 
'j hit 17';
?>

The above example will output:

j hit 17

Example #3 This will not work

<?php
goto loop;
for(
$i=0,$j=50$i<100$i++) {
  while(
$j--) {
    
loop:
  }
}
echo 
"$i = $i";
?>

The above example will output:

Fatal error: 'goto' into loop or switch statement is disallowed in
script on line 2

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User Contributed Notes 2 notes

up
3
Lollo
1 month ago
You should mention the label can't be a variable
up
0
instatiendaweb at gmail dot com
4 days ago
$array = array();
for ($i = 0; $i <= 10; (int)$array[] = $i, $i++);

var_dump($array );
$countarray = (count($array) - 2) ;

var_dump($countarray);

static $goto = 0;
/***************************************************************************************************/
b:

$array[$goto] = $array[$goto] * 2;

if ($goto <= $countarray){
    $goto++;
    goto b;
}else{
    goto a;}
a:
/***************************************************************************************************/
var_dump($array);
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