Php-Iterator interface

The Iterator interface, a predefined PHP interface, can iterate its own external Iterator or class interface internally.

Interface abstract

Iterator extends Traversable {/* method */abstract public mixed current (void) abstract public scalar key (void) abstract public void next (void) abstract public void rewind (void) abstract public boolean valid (void )}

Pre-defined iterator

PHP already provides some iterators for daily tasks, such as SPL iterators.

Example

Example #1 Basic usage

This example shows the call sequence of the iterator method when foreach is used.

 position = 0;        }        function rewind() {            var_dump(__METHOD__);            $this->position = 0;        }        function current() {            var_dump(__METHOD__);            return $this->array[$this->position];        }        function key() {            var_dump(__METHOD__);            return $this->position;        }        function next() {            var_dump(__METHOD__);            ++$this->position;        }        function valid() {            var_dump(__METHOD__);            return isset($this->array[$this->position]);        }    }    $it = new myIterator;    foreach($it as $key => $value) {        var_dump($key, $value);        echo "\n";    }?>

The output of the preceding routine is similar:

string(18) "myIterator::rewind"string(17) "myIterator::valid"string(19) "myIterator::current"string(15) "myIterator::key"int(0)string(12) "firstelement"string(16) "myIterator::next"string(17) "myIterator::valid"string(19) "myIterator::current"string(15) "myIterator::key"int(1)string(13) "secondelement"string(16) "myIterator::next"string(17) "myIterator::valid"string(19) "myIterator::current"string(15) "myIterator::key"int(2)string(11) "lastelement"string(16) "myIterator::next"string(17) "myIterator::valid"

Method list

Iterator: current-returns the current element

Iterator: key-return the key of the current element

Iterator: next-move forward to the next element

Iterator: rewind-the first element returned to the Iterator

Iterator: valid-check whether the current location is valid