PHP 7.2.0 Beta 1 Released

break

(PHP 4, PHP 5, PHP 7)

break 结束当前 forforeachwhiledo-while 或者 switch 结构的执行。

break 可以接受一个可选的数字参数来决定跳出几重循环。

<?php
$arr 
= array('one''two''three''four''stop''five');
while (list (, 
$val) = each($arr)) {
    if (
$val == 'stop') {
        break;    
/* You could also write 'break 1;' here. */
    
}
    echo 
"$val<br />\n";
}

/* 使用可选参数 */

$i 0;
while (++
$i) {
    switch (
$i) {
    case 
5:
        echo 
"At 5<br />\n";
        break 
1;  /* 只退出 switch. */
    
case 10:
        echo 
"At 10; quitting<br />\n";
        break 
2;  /* 退出 switch 和 while 循环 */
    
default:
        break;
    }
}
?>

break 的更新记录
版本 说明
5.4.0 break 0; 不再合法。这在之前的版本被解析为 break 1;
5.4.0 取消变量作为参数传递(例如 $num = 2; break $num;)。

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User Contributed Notes 4 notes

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110
steve at electricpocket dot com
5 years ago
A break statement that is in the outer part of a program (e.g. not in a control loop) will end the script. This caught me out when I mistakenly had a break in an if statement

i.e.

<?php
echo "hello";
if (
true) break;
echo
" world";
?>

will only show "hello"
up
13
traxer at gmx dot net
11 years ago
vlad at vlad dot neosurge dot net wrote on 04-Jan-2003 04:21

> Just an insignificant side not: Like in C/C++, it's not
> necessary to break out of the default part of a switch
> statement in PHP.

It's not necessary to break out of any case of a switch  statement in PHP, but if you want only one case to be executed, you have do break out of it (even out of the default case).

Consider this:

<?php
$a
= 'Apple';
switch (
$a) {
    default:
        echo
'$a is not an orange<br>';
    case
'Orange':
        echo
'$a is an orange';
}
?>

This prints (in PHP 5.0.4 on MS-Windows):
$a is not an orange
$a is an orange

Note that the PHP documentation does not state the default part must be the last case statement.
up
4
RK
6 years ago
If the numerical argument is higher than the number of things which can be broken out of, it seems to me like the execution of the entire program is stopped.
My program had 8 nested loops. Didn't bother counting them, but wrote: break 10. - Result: Code following the loops was not processed.
up
0
Anonymous
10 years ago
If you wonder how to end execution of a function (as I did), it's that simple: return

function foo($a) {
if(!$a) return;
echo 'true';
// some other code
}

foo(true) will echo 'true', foo(false) won't echo anything (as return ends execution of the function. Of course, therefore there is no need for 'else' before 'echo').
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