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CachingIterator::offsetExists

(PHP 5 >= 5.2.0, PHP 7)

CachingIterator::offsetExistsThe offsetExists purpose

说明

public CachingIterator::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

Returns TRUE if an entry referenced by the offset exists, FALSE otherwise.

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User Contributed Notes 1 note

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ddrake at dreamingmind dot com
10 months ago
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
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