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PHP Quiz PHP CertificatePHP 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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