PHP array_key_exists() Function

In this chapter you will learn:

  1. Definition for PHP array_key_exists() Function
  2. Syntax for PHP array_key_exists() Function
  3. Parameter for PHP array_key_exists() Function
  4. Return value from PHP array_key_exists() Function
  5. Example - Check if the key "j" exists in an array
  6. Example - Check if the integer key "0" exists in an array

Definition

The array_key_exists() function checks existence of a specified key in an array.

Syntax

PHP array_key_exists() Function has the following syntax.

array_key_exists(key,array)

Parameter

ParameterIs RequiredDescription
keyRequired.Key to look for
arrayRequired.Array to look for

Return

PHP array_key_exists() Function returns true if the key exists and false if the key does not exist.

Example 1

Check if the key "j" exists in an array:


<?php/* j  a v  a 2 s .co  m*/
    $a=array("a"=>"A","b"=>"Bed","c"=>"Cat","j"=>"java2s.com");
    if (array_key_exists("j",$a)){
      echo "Key exists!";
    }else{
      echo "Key does not exist!";
    }
?>

The code above generates the following result.

Example 2

Check if the integer key "0" exists in an array:


<?php/*jav  a  2 s .c o  m*/
    $a=array("PHP","Java");
    if (array_key_exists(0,$a)){
      echo "Key exists!";
    }else{
      echo "Key does not exist!";
    }
?>

The code above generates the following result.

Next chapter...

What you will learn in the next chapter:

  1. Definition for PHP array_keys() function
  2. Syntax for PHP array_keys() function
  3. Parameter for PHP array_keys() function
  4. Example - Get all keys in an array
  5. Example - Get all keys for an associate array
  6. Example - Using the strict parameter, false
  7. Example - Using the strict parameter, true
Home » PHP Tutorial » PHP Array Functions
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