如何按位置获取PHP数组中的键? [英] How to get the keys in a PHP Array by position?

问题描述

我有一个数组，仅当值不为null时才存储键值对.我想知道如何检索数组中的键?

 <?php$ pArray = Array();if(！is_null($ params ['Name']))$ pArray ["Name"] = $ params ['Name'];if(！is_null($ params ['Age']))$ pArray ["Age"] = $ params ['Age'];if(！is_null($ params ['Salary']))$ pArray ["Salary"] = $ params ['Salary'];if(count($ pArray)> 0){//遍历数组，并通过一个键获取键...}?> 

感谢您的帮助

解决方案

PHP的foreach循环具有允许您在键/值对上循环的运算符.非常方便:

  foreach($ pArray as $ key => $ value){打印$ key}//如果您只想选择第一个键，我将执行以下操作:foreach($ pArray as $ key => $ value){打印$ key;休息;} 

此方法的替代方法是调用 reset() 并然后 key() :

  reset($ pArray);$ first_key =键($ pArray); 

它与 foreach()中发生的事情基本上相同，但是根据

Thanks for helping

解决方案

PHP's foreach loop has operators that allow you to loop over Key/Value pairs. Very handy:

foreach ($pArray as $key => $value)
{
    print $key
}

//if you wanted to just pick the first key i would do this: 

    foreach ($pArray as $key => $value)
{
    print $key;
    break;
}

An alternative to this approach is to call reset() and then key():

reset($pArray);
$first_key = key($pArray);

It's essentially the same as what is happening in the foreach(), but according to this answer there is a little less overhead.

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