The AppendIterator::valid() function is an inbuilt function in PHP which is used to check the validity of the current element.
Syntax:
bool AppendIterator::valid( void )
Parameters: This function does not accept any parameters.
Return Value: This function returns TRUE if the current iteration is valid and FALSE otherwise.
Below programs illustrate the AppendIterator::valid() function in PHP:
Program 1:
<?php    // Declare an ArrayIterator $arr = new ArrayIterator( array ( 'G' , 'e' , 'e' , 'k' , 's' ));    // Create a new AppendIterator $itr = new AppendIterator; $itr ->append( $arr );    // Check the validity and display // the result while ( $itr ->valid()) {     echo $itr ->current();     $itr ->next(); }    ?> |
Geeks
Program 2:
<?php     // Declare an ArrayIterator $arr1 = new ArrayIterator( array ( "Geeks" , "for" , "Geeks" )); $arr2 = new ArrayIterator( array ( "Computer" , "Science" , "Portal" ));    // Create a new AppendIterator $itr = new AppendIterator; $itr ->append( $arr1 ); $itr ->append( $arr2 );    // Using rewind function $itr -> rewind ();    // Check the validity and display the result while ( $itr ->valid()) {     var_dump( $itr ->current());              // Moving to next element     $itr ->next(); }     ?> |
string(5) "Geeks" string(3) "for" string(5) "Geeks" string(8) "Computer" string(7) "Science" string(6) "Portal"
Reference: https://www.php.net/manual/en/appenditerator.valid.php