问题描述
我有一个数据库调用，我试图找出什么 $键=＆GT; $值确实在的foreach 循环。
I have a database call and I'm trying to figure out what the $key => $value does in a foreach loop.
我想问的原因是因为这两个codeS输出同样的事情，所以我试图理解它为什么这样写。这里的code：
The reason I ask is because both these codes output the same thing, so I'm trying to understand why it's written this way. Here's the code:
foreach($featured as $key => $value){
echo $value['name'];
}
这输出为：
foreach($featured as $value) {
echo $value['name']
}
所以我的问题是，什么是 $键=＆GT之间的差异; $值或只是 $值在的foreach 循环。该数组是多维的，如果有差别，我只是想知道为什么通过 $键到 $值中在的foreach 循环。
So my question is, what is the difference between $key => $value or just $value in the foreach loop. The array is multidimensional if that makes a difference, I just want to know why to pass $key to $value in the foreach loop.
推荐答案
那么， $键=＆GT; $值在foreach循环是指关联数组的键值对，其中键作为指标来确定，而不是一个像0,1,2的值，...在PHP，关联数组是这样的：
Well, the $key => $value in the foreach loop refers to the key-value pairs in associative arrays, where the key serves as the index to determine the value instead of a number like 0,1,2,... In PHP, associative arrays look like this:
$featured = array('key1' => 'value1', 'key2' => 'value2', etc.);
在PHP code： $特色正在通过循环关联数组和为$关键=＆GT; $值表示，每次循环运行，并选择从阵列中键值对，它存储在本地 $键变量的关键在循环块，并在当地 $值变量的值内使用。因此，对于我们上面的例子数组，foreach循环将到达第一个键值对，如果你指定的为$关键=＆GT; $值，它将存储键1 在 $键变量和VALUE1在 $值变量。
In the PHP code: $featured is the associative array being looped through, and as $key => $value means that each time the loop runs and selects a key-value pair from the array, it stores the key in the local $key variable to use inside the loop block and the value in the local $value variable. So for our example array above, the foreach loop would reach the first key-value pair, and if you specified as $key => $value, it would store 'key1' in the $key variable and 'value1' in the $value variable.
既然你不使用 $键你的循环块内的变量，将它添加或移除它不会改变环路的输出，但它是最好的包括键值对，以表明它是一个关联数组。
Since you don't use the $key variable inside your loop block, adding it or removing it doesn't change the output of the loop, but it's best to include the key-value pair to show that it's an associative array.
另外请注意，为$关键=＆GT; $值指定是任意的。你可以用替换为$富=＆GT; $栏，当你改变了循环块内的变量引用到新的变量，它会很好，只要努力， $ foo的和 $栏。但让他们 $键和 $值有助于跟踪他们的意思。
Also note that the as $key => $value designation is arbitrary. You could replace that with as $foo => $bar and it would work fine as long as you changed the variable references inside the loop block to the new variables, $foo and $bar. But making them $key and $value helps to keep track of what they mean.
这篇关于为$关键=＆GT;＆QUOT之间的差异; $值＆QUOT;和＆QUOT;为$值＆QUOT;在PHP的foreach的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！