PHP array function array_key_exists() finds whether the array key exists

Contents of this section: PHP array function array_key_exists()

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

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

Example 1, PHP array function array_key_exists().

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

Output: Key exists!

Example 2, PHP array function array_key_exists().

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

Output: Key does not exist!

Example 3, PHP array function array_key_exists().

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

Output: Key exists!