In-depth analysis of array_keys() in PHP

Arrays are a common data type in PHP. During normal use, we may often need to obtain the key name of the array. PHP provides array_keys() This article will take you to take a look at this function.

First, let’s take a look at the syntax of <span style="font-family: 微软雅黑, " microsoft yahei background-color: rgb color:>array_keys()</span><span style="font-family: 微软雅黑, " microsoft yahei background-color: rgb color:></span><span style="font-family: 微软雅黑, " microsoft yahei background-color: rgb color:></span>##.

array_keys ( array $array   , mixed $search_value = null   , bool $strict = false   )

• $array: The array to be viewed.
  

• $search_vaule: The default value is empty. If this parameter is specified, only key names containing these values ​​will be returned.

• $strict: Determine whether strict comparison (===) should be used when searching

• Return value: index array of array type

Actual experience:

a. There is only one parameter:

<?php
     $ace=array("one","two","three","four","Three");
     print_r(array_keys($ace));

输出：Array ( [0] => 0 [1] => 1 [2] => 2 [3] => 3 [4] => 4 )

b. There are only two parameters

<?php
   $ace=array("one","two","three","four","Three");
    print_r(array_keys($ace,"three"));
?>

输出：Array ( [0] => 2 )

c. There are three parameters:

<?php
   $ace2=array("one","two","three","four","10",10);
     print_r(array_keys($ace2,"10"));
      echo "<br>";
     print_r(array_keys($ace2,"10",true));
?>

输出：Array ( [0] => 4 [1] => 5 )
      Array ( [0] => 4 )

We can see that when the third parameter is

true, array_keys () Enables a more stringent comparison.

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