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PHP array_key_exists() Function
Complete PHP Array Reference
Definition and Usage
The array_key_exists() function checks an array for a specified key, and returns true if the key exists and false if the key does not exist.
Syntax
array_key_exists(key,array)
| Parameter | Description |
|---|---|
| key | Required. Specifies the key |
| array | Required. Specifies an array |
Tips and Notes
Tip: Remember that if you skip the key when you specify an array, an integer key is generated, starting at 0 and increases by 1 for each value. (See example 3)
Example 1
<?php
$a=array("a"=>"Dog","b"=>"Cat");
if (array_key_exists("a",$a))
{
echo "Key exists!";
}
else
{
echo "Key does not exist!";
}
?>
$a=array("a"=>"Dog","b"=>"Cat");
if (array_key_exists("a",$a))
{
echo "Key exists!";
}
else
{
echo "Key does not exist!";
}
?>
The output of the code above will be:
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!";
}
?>
$a=array("a"=>"Dog","b"=>"Cat");
if (array_key_exists("c",$a))
{
echo "Key exists!";
}
else
{
echo "Key does not exist!";
}
?>
The output of the code above will be:
Key does not exist!
Example 3
<?php
$a=array("Dog",Cat");
if (array_key_exists(0,$a))
{
echo "Key exists!";
}
else
{
echo "Key does not exist!";
}
?>
$a=array("Dog",Cat");
if (array_key_exists(0,$a))
{
echo "Key exists!";
}
else
{
echo "Key does not exist!";
}
?>
The output of the code above will be:
Key exists!
Complete PHP Array Reference
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W3Schools is optimized for learning, testing, and training. Examples might be simplified to improve reading and basic understanding.
Tutorials, references, and examples are constantly reviewed to avoid errors, but we cannot warrant full correctness of all content.
While using this site, you agree to have read and accepted our terms of use and privacy policy.
Copyright 1999-2012 by Refsnes Data. All Rights Reserved.
Tutorials, references, and examples are constantly reviewed to avoid errors, but we cannot warrant full correctness of all content.
While using this site, you agree to have read and accepted our terms of use and privacy policy.
Copyright 1999-2012 by Refsnes Data. All Rights Reserved.