break
The remark "in PHP the switch statement is considered a looping structure for the purposes of continue" near the top of this page threw me off, so I experimented a little using the following code to figure out what the exact semantics of continue inside a switch is:
<?php
for( $i = 0; $i < 3; ++ $i )
{
echo ' [', $i, '] ';
switch( $i )
{
case 0: echo 'zero'; break;
case 1: echo 'one' ; XXXX;
case 2: echo 'two' ; break;
}
echo ' <' , $i, '> ';
}
?>
For XXXX I filled in
- continue 1
- continue 2
- break 1
- break 2
and observed the different results. This made me come up with the following one-liner that describes the difference between break and continue:
continue resumes execution just before the closing curly bracket ( } ), and break resumes execution just after the closing curly bracket.
Corollary: since a switch is not (really) a looping structure, resuming execution just before a switch's closing curly bracket has the same effect as using a break statement. In the case of (for, while, do-while) loops, resuming execution just prior their closing curly brackets means that a new iteration is started --which is of course very unlike the behavior of a break statement.
In the one-liner above I ignored the existence of parameters to break/continue, but the one-liner is also valid when parameters are supplied.
continue
(PHP 4, PHP 5)
continue se utiliza dentro de las estructuras iterativas para saltar el resto de la iteración actual del bucle y continuar la ejecución en la evaluación de la condición, y luego comenzar la siguiente iteración.
Nota: Tenga en cuenta que en PHP la sentencia switch se considera una estructura iterativa para los propósitos de continue.
continue acepta un argumento numérico opcional, que indica a cuántos niveles de bucles encerrados se ha de saltar al final. El valor por omisión es 1, por lo que salta al final del bucle actual.
<?php
while (list($clave, $valor) = each($arr)) {
if (!($clave % 2)) { // saltar los miembros impares
continue;
}
hacer_algo($valor);
}
$i = 0;
while ($i++ < 5) {
echo "Exterior<br />\n";
while (1) {
echo "Medio<br />\n";
while (1) {
echo "Interior<br />\n";
continue 3;
}
echo "Esto nunca se imprimirá.<br />\n";
}
echo "Ni esto tampoco.<br />\n";
}
?>
Omitir el punto y coma después del continue puede llevar a confusión. He aquí un ejemplo de lo que no se debe hacer.
<?php
for ($i = 0; $i < 5; ++$i) {
if ($i == 2)
continue
print "$i\n";
}
?>
Se esperaría que el resultado fuera:
0 1 3 4
pero la salida de este script será:
2
debido a que continue print "$i\n"; se evalúa completo como una sola expresión, y así print se llama solamente cuando $i == 2 es verdadero. (El valor de retorno de print es pasado a continue como el argumento numérico.)
| Versión | Descripción |
|---|---|
| 5.4.0 | continue 0; ya no es válido. En versiones anteriores era interpretado de la misma manera que continue 1;. |
| 5.4.0 | Se eliminó la posibilidad de pasar variables (por ejemplo, $num = 2; continue $num;) como el argumento numérico. |
add a note
User Contributed Notes
continue - [17 notes]
jaimthorn at yahoo dot com ¶
3 years ago
rjsteinert.com ¶
2 years ago
The most basic example that print "13", skipping over 2.
<?php
$arr = array(1, 2, 3);
foreach($arr as $number) {
if($number == 2) {
continue;
}
print $number;
}
?>
dedlfix gives me a hint ¶
8 years ago
a possible solution for
greg AT laundrymat.tv
I've got the same problem as Greg
and now it works very fine by using
return() instead of continue.
It seems, that you have to use return()
if you have a file included and
you want to continue with the next loop
greg AT laundrymat.tv ¶
8 years ago
You using continue in a file included in a loop will produce an error. For example:
//page1.php
for($x=0;$x<10;$x++)
{
include('page2.php');
}
//page2.php
if($x==5)
continue;
else
print $x;
it should print
"012346789" no five, but it produces an error:
Cannot break/continue 1 level in etc.
www.derosetechnologies.com ¶
9 years ago
In the same way that one can append a number to the end of a break statement to indicate the "loop" level upon which one wishes to 'break' , one can append a number to the end of a 'continue' statement to acheive the same goal. Here's a quick example:
<?
for ($i = 0;$i<3;$i++) {
echo "Start Of I loop\n";
for ($j=0;;$j++) {
if ($j >= 2) continue 2; // This "continue" applies to the "$i" loop
echo "I : $i J : $j"."\n";
}
echo "End\n";
}
?>
The output here is:
Start Of I loop
I : 0 J : 0
I : 0 J : 1
Start Of I loop
I : 1 J : 0
I : 1 J : 1
Start Of I loop
I : 2 J : 0
I : 2 J : 1
For more information, see the php manual's entry for the 'break' statement.
maik penz ¶
1 year ago
Please note that with PHP 5.4 continue 0; will fail with
PHP Fatal error: 'continue' operator accepts only positive numbers
(same is true for break).
Koen ¶
5 months ago
If you use a incrementing value in your loop, be sure to increment it before calling continue; or you might get an infinite loop.
Anonymous ¶
4 years ago
The continue keyword can skip division by zero:
<?php
$i = 100;
while ($i > -100)
{
$i--;
if ($i == 0)
{
continue;
}
echo (200 / $i) . "<br />";
}
?>
Geekman ¶
5 years ago
For clarification, here are some examples of continue used in a while/do-while loop, showing that it has no effect on the conditional evaluation element.
<?php
// Outputs "1 ".
$i = 0;
while ($i == 0) {
$i++;
echo "$i ";
if ($i == 1) continue;
}
// Outputs "1 2 ".
$i = 0;
do {
$i++;
echo "$i ";
if ($i == 2) continue;
} while ($i == 1);
?>
Both code snippets would behave exactly the same without continue.
tufan dot oezduman at gmail dot com ¶
6 years ago
a possible explanation for the behavior of continue in included scripts mentioned by greg and dedlfix above may be the following line of the "return" documentation: "If the current script file was include()ed or require()ed, then control is passed back to the calling file."
The example of greg produces an error since page2.php does not contain any loop-operations.
So the only way to give the control back to the loop-operation in page1.php would be a return.
szrrya at yahoo dot com ¶
6 years ago
Documentation states:
"continue is used within looping structures to skip the rest of the current loop iteration"
Current functionality treats switch structures as looping in regards to continue. It has the same effect as break.
The following code is an example:
<?php
for ($i1 = 0; $i1 < 2; $i1++) {
// Loop 1.
for ($i2 = 0; $i2 < 2; $i2++) {
// Loop 2.
switch ($i2 % 2) {
case 0:
continue;
break;
}
print '[' . $i2 . ']<br>';
}
print $i1 . '<br>';
}
?>
This outputs the following:
[0]
[1]
0
[0]
[1]
1
Switch is documented as a block of if...elseif... statements, so you might expect the following output:
[1]
0
[1]
1
This output requires you to either change the switch to an if or use the numerical argument and treat the switch as one loop.
net_navard at yahoo dot com ¶
7 years ago
Hello firends
It is said in manually:
continue also accepts an optional numeric argument which tells it how many levels of enclosing loops it should .
In order to understand better this,An example for that:
<?php
/*continue also accepts an optional numeric argument which
tells it how many levels of enclosing loops it should skip.*/
for($k=0;$k<2;$k++)
{//First loop
for($j=0;$j<2;$j++)
{//Second loop
for($i=0;$i<4;$i++)
{//Third loop
if($i>2)
continue 2;// If $i >2 ,Then it skips to the Second loop(level 2),And starts the next step,
echo "$i\n";
}
}
}
?>
Merry's christmas :)
With regards,Hossein
Rene ¶
7 years ago
(only) the reason that is given on the "Continue with missing semikolon" example is wrong.
the script will output "2" because the missing semikolon causes that the "print"-call is executed only if the "if" statement is true. It has nothing to to with "what" the "print"-call would return or not return, but the returning value can cause to skip to the end of higher level Loops if any call is used that will return a bigger number than 1.
<?php
continue print "$i\n";
?>
because of the optional argument, the script will not run into a "unexpected T_PRINT" error. It will not run into an error, too, if the call after continue does return anything but a number.
i suggest to change it from:
because the return value of the print() call is int(1), and it will look like the optional numeric argument mentioned above.
to
because the print() call will look like the optional numeric argument mentioned above.
Anonymous ¶
1 year ago
<?php
function print_primes_between($x,$y)
{
for($i=$x;$i<=$y;$i++)
{
for($j= 2; $j < $i; $j++) if($i%$j==0) continue 2;
echo $i.",";
}
}
?>
This function, using continue syntax, is to print prime numbers between given numbers, x and y.
For example, print_primes_between(10,20) will output:
11,13,17,19,23,29,
skippychalmers at gmail dot com ¶
2 years ago
To state the obvious, it should be noted, that the optional param defaults to 1 (effectively).
Nikolay Ermolenko ¶
4 years ago
Using continue and break:
<?php
$stack = array('first', 'second', 'third', 'fourth', 'fifth');
foreach($stack AS $v){
if($v == 'second')continue;
if($v == 'fourth')break;
echo $v.'<br>';
}
/*
first
third
*/
$stack2 = array('one'=>'first', 'two'=>'second', 'three'=>'third', 'four'=>'fourth', 'five'=>'fifth');
foreach($stack2 AS $k=>$v){
if($v == 'second')continue;
if($k == 'three')continue;
if($v == 'fifth')break;
echo $k.' ::: '.$v.'<br>';
}
/*
one ::: first
four ::: fourth
*/
?>
Anonymous ¶
3 years ago
Example regarding the condition at the end of the loop and continue:
<?php
$i = 0;
do {
printf('%d ', $i);
continue;
} while( ++$i < 10);
// Output: 0 1 2 3 4 5 6 7 8 9
?>
It gets executed all the time regardless that continue is placed before the while() statement. That does not get skipped.