PHP：限制 foreach() 语句？

PHP: Limit foreach() statement?

提问by tarnfeld

How can i limit a foreach() statement? Say i only want it to run the first 2 'eaches' or something?

如何限制 foreach() 语句？说我只希望它运行前 2 个 'eaches' 之类的？

回答by reko_t

There are many ways, one is to use a counter:

方法很多，一种是使用计数器：

$i = 0;
foreach ($arr as $k => $v) {
    /* Do stuff */
    if (++$i == 2) break;
}

Other way would be to slice the first 2 elements, this isn't as efficient though:

另一种方法是对前 2 个元素进行切片，但这并不那么有效：

foreach (array_slice($arr, 0, 2) as $k => $v) {
    /* Do stuff */
}

You could also do something like this (basically the same as the first foreach, but with for):

你也可以做这样的事情（与第一个 foreach 基本相同，但使用 for）：

for ($i = 0, reset($arr); list($k,$v) = each($arr) && $i < 2; $i++) {
}

回答by Valentin Golev

You can either use

您可以使用

break;

or

或者

foreach() if ($tmp++ < 2) {
}

(the second solution is even worse)

（第二种解决方案更糟糕）

回答by RageZ

you should use the breakstatement

你应该使用break语句

usually it's use this way

通常它是这样使用的

$i = 0;
foreach($data as $key => $row){
    if(++$i > 2) break;
}

on the same fashion the continuestatement exists if you need to skip some items.

如果您需要跳过某些项目，则以同样的方式存在continue语句。

回答by Tgr

In PHP 5.5+, you can do

在 PHP 5.5+ 中，你可以这样做

function limit($iterable, $limit) {
    foreach ($iterable as $key => $value) {
        if (!$limit--) break;
        yield $key => $value;
    }
}

foreach (limit($arr, 10) as $key => $value) {
    // do stuff
}

Generatorsrock.

发电机摇滚。

回答by tcgumus

this is best solution for me :)

这对我来说是最好的解决方案:)

$i=0;
foreach() if ($i < yourlimitnumber) {

$i +=1;
}