PHP array function sequence array_key_exists() - Find whether the array key exists

array_key_exists() Definition and usage
array_key_exists() function determines whether the specified key exists in an array. If the key exists, it returns true, otherwise it returns false.

Syntax
array_key_exists(key,array)
Parameter Description
key required. Specifies the key name.
array required. Specifies the input array.

Example 1

<?php 
$a=array("a"=>"Dog","b"=>"Cat"); 
if (array_key_exists("a",$a)) 
{ 
echo "Key exists!"; 
} 
else 
{ 
echo "Key does not exist!"; 
} 
?>

Output:

Key exists!
Example 2

<?php 
$a=array("a"=>"Dog","b"=>"Cat"); 
if (array_key_exists("c",$a)) 
{ 
echo "Key exists!"; 
} 
else 
{ 
echo "Key does not exist!"; 
} 
?>

Output:

Key does not exist !
Example 2

<?php 
$a=array("Dog",Cat"); 
if (array_key_exists(0,$a)) 
{ 
echo "Key exists!"; 
} 
else 
{ 
echo "Key does not exist!"; 
} 
?>

Output:

Key exists!

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