array_keys

PHP array_keys()函数 (PHP array_keys() function)

array_keys() function is used to get the keys of an array, it accepts an array as an argument and returns a new array containing keys.

array_keys()函数用于获取数组的键，它接受一个数组作为参数并返回一个包含键的新数组。

Syntax:

句法：

    array_keys(input_array, [value], [strict]);

Here,

这里，

• input_array is an array (i.e. input array).

  input_array是一个数组(即输入数组)。

• value is an optional parameter, it is used to define a value if the value is defined, then the only keys having that value are returned.

  value是一个可选参数，如果定义了值，则用于定义值，然后仅返回具有该值的键。

• strict is also an optional parameter, it is default set to false if we set it true the type of values will be checked.

  严格也是一个可选的参数，它是默认设置为false，如果我们把它真值的类型将被检查。

Examples:

例子：

    Input:
$per = array("name" => "Amit", "age" => 21, "gender" => "Male");
Output:
Array
(
[0] => name
[1] => age
[2] => gender
)

PHP code 1: array with and without containing keys

PHP代码1：包含和不包含键的数组

<?php
$per = array("name" => "Amit", "age" => 21, "gender" => "Male");
print ("keys array...\n");
print_r (array_keys($per));
//array with out keys
$arr = array("Hello", "world", 100, 200, -10);
print ("keys array...\n");
print_r (array_keys($arr));
?>

Output

输出量

keys array...
Array
(
[0] => name
[1] => age
[2] => gender
)
keys array...
Array
(
[0] => 0
[1] => 1
[2] => 2
[3] => 3
[4] => 4
)

PHP code 2: Using value and strict mode

PHP代码2：使用值和严格模式

<?php
$arr = array("101" => 100, "102" => "100", "103" => 200);
print("output (default function call)...\n");
print_r (array_keys($arr));
print("output (with checking value)...\n");
print_r (array_keys($arr, 100));
print("output (with checking value & strict mode)...\n");
print_r (array_keys($arr, 100, true));
?>

Output

输出量

output (default function call)...
Array
(
[0] => 101
[1] => 102
[2] => 103
)
output (with checking value)...
Array
(
[0] => 101
[1] => 102
)
output (with checking value & strict mode)...
Array
(
[0] => 101
)

翻译自: https://www.includehelp.com/php/array_keys-function-with-example.aspx

array_keys