How to determine whether the specified key exists in PHP

In PHP, you can use the "array_key_exists()" function to determine whether the specified key exists. The function of this function is to check whether the specified key name exists in an array; the syntax is "array_key_exists(key name) , array)", returns true if it exists, otherwise returns false.

The operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer

In php, you can use " array_key_exists()" function to determine whether the specified key exists.

array_key_exists() function checks whether the specified key exists in an array. If the key exists, it returns true. If the key does not exist, it returns false.

Syntax:

array_key_exists($key,$array)

• $key: Required. Specifies the key name.

• $array : Required. Specifies an array.

Example: Check if the key "Toyota" exists in the array

<?php
header("Content-type:text/html;charset=utf-8");
$a=array("Volvo"=>"XC90","BMW"=>"X5");
if (array_key_exists("Toyota",$a))
{
    echo "指定键存在";
}
else
{
    echo "指定键不存在";
}
?>

Tip: Remember, If you omit the keys when specifying an array, integer keys will be generated starting from 0 and increasing by 1.

Recommended learning: "PHP Video Tutorial", "PHP ARRAY"

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