CachingIterator::offsetExists()

(PHP 5>=5.2.0,PHP 7)

The offsetExists purpose

说明

publicCachingIterator::offsetExists(mixed $index) : void

Warning

本函数还未编写文档，仅有参数列表。

参数

$index

The index being checked.

返回值

ReturnsTRUEif an entry referenced by the offset exists,FALSEotherwise.

offsetExists($index) examines the cache, not the inner or outer iterator.
<?php
    $cache = new \CachingIterator(
      new \ArrayIterator(['a', 'b', 'c', 'd']),
      \CachingIterator::FULL_CACHE);
    $shortRange = range(0, 1);
    $fullRange = range(0, 3);
    foreach ($shortRange as $index) {
      $cache->next();
    }
    echo PHP_EOL . 'The cache' . PHP_EOL;
    var_export($cache->getCache());
    echo PHP_EOL;
    foreach ($fullRange as $offset) {
      print_r("cache offset '$offset' " .
        ($cache->offsetExists("$offset") == 1
          ? 'exists'
          : "doesn't exist"
        ) . PHP_EOL);
    }
?>
The cache
array (
 0 => 'a',
 1 => 'b',
)
cache offset '0' exists
cache offset '1' exists
cache offset '2' doesn't exist
cache offset '3' doesn't exist