PHP SplHeap valid() Function

The SplHeap::valid() function is an inbuilt function in PHP which is used to check whether the heap contains more nodes.

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:

bool SplHeap::valid()

Parameters: This function does not accept any parameters.

Return Value: This function returns true if the heap contains any more nodes, false otherwise. 

Below programs illustrate the SplHeap::valid() function in PHP:

Example 1:

PHP

<?php

// Create a new empty Min Heap
$heap = new SplMinHeap();

$heap->insert('System');
$heap->insert('GFG');
$heap->insert('ALGO');
$heap->insert('C');
$heap->insert('Geeks');
$heap->insert('GeeksforGeeks');

// Loop to display the current element of heap
for ($heap->top(); $heap->valid(); $heap->next()) {
    echo $heap->current() . "\n";
}

?>

Output

ALGO
C
GFG
Geeks
GeeksforGeeks
System

Example 2:

PHP

<?php

// Create a new empty Max Heap
$heap = new SplMaxHeap();

$heap->insert('System');
$heap->insert('GFG');
$heap->insert('ALGO');
$heap->insert('C');
$heap->insert('Geeks');
$heap->insert('GeeksforGeeks');

// Loop to display the current element of heap
for ($heap->top(); $heap->valid(); $heap->next()) {
    echo $heap->current() . "\n";
}

?>

Output

System
GeeksforGeeks
Geeks
GFG
C
ALGO

Reference: https://www.php.net/manual/en/splheap.valid.php