PHP SplHeap valid() Function

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

Output

ALGO
C
GFG
Geeks
zambiatek
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('zambiatek');  
  
// Loop to display the current element of heap 
for ($heap->top(); $heap->valid(); $heap->next()) { 
    echo $heap->current() . "\n"; 
} 
  
?>