PHP SplHeap key() Function
Last Updated :
26 Mar, 2021
The SplHeap::key() function is an inbuilt function in PHP which is used to get the current node index.
Generally, the Heap Data Structure are of two types:
- Max-Heap: In a Max-Heap the key present at the root node must be greatest among the keys present at all of its children. The same property must be recursively true for all sub-trees in that Binary Tree.
- Min-Heap: In a Min-Heap the key present at the root node must be minimum among the keys present at all of its children. The same property must be recursively true for all sub-trees in that Binary Tree.
Syntax:
mixed SplHeap::key()
Parameters: This function does not accept any parameter.
Return Value: This function returns the key of current node.
Below programs illustrate the SplHeap::key() function in PHP:
Example 1:
PHP
<?php
$heap = new SplMinHeap();
$heap ->insert( 'System' );
$heap ->insert( 'GFG' );
$heap ->insert( 'ALGO' );
$heap ->insert( 'C' );
$heap ->insert( 'Geeks' );
$heap ->insert( 'GeeksforGeeks' );
for ( $heap ->top(); $heap ->valid(); $heap ->next()) {
echo "Key => " . $heap ->key()
. ", Value => " . $heap ->current() . "\n" ;
}
?>
|
Output:
Key => 5, Value => ALGO
Key => 4, Value => C
Key => 3, Value => GFG
Key => 2, Value => Geeks
Key => 1, Value => GeeksforGeeks
Key => 0, Value => System
Example 2:
PHP
<?php
$heap = new SplMaxHeap();
$heap ->insert( 'System' );
$heap ->insert( 'GFG' );
$heap ->insert( 'ALGO' );
$heap ->insert( 'C' );
$heap ->insert( 'Geeks' );
$heap ->insert( 'GeeksforGeeks' );
for ( $heap ->top(); $heap ->valid(); $heap ->next()) {
echo "Key => " . $heap ->key()
. ", Value => " . $heap ->current() . "\n" ;
}
?>
|
Output:
Key => 5, Value => System
Key => 4, Value => GeeksforGeeks
Key => 3, Value => Geeks
Key => 2, Value => GFG
Key => 1, Value => C
Key => 0, Value => ALGO
Reference: https://www.php.net/manual/en/splheap.key.php
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