php - 设置内部数组指针而不在 PHP 中迭代

Question

是否可以在不先遍历数组的情况下设置 PHP 的内部数组指针。以下面的伪代码为例:

$array = range(1, 100);

// Represents the array key
$pointer = 66;

set_array_pointer($pointer, $array);

$nextValue = next($array); // Should return 68

Answer 1

LibertyPaul 使用 ArrayIterator::seek 提供的解决方案似乎是使 php 将指针设置为数组中某个位置而无需在用户空间中初始化循环的唯一方法。不过，php 将在内部循环遍历数组以设置指针，正如您可以从 php source 中读取的那样。 ArrayIterator::seek() 的:

/* {{{ proto void ArrayIterator::seek(int $position)
   Seek to position. */
SPL_METHOD(Array, seek)
{
    zend_long opos, position;
    zval *object = getThis();
    spl_array_object *intern = Z_SPLARRAY_P(object);
    HashTable *aht = spl_array_get_hash_table(intern);
    int result;

    if (zend_parse_parameters(ZEND_NUM_ARGS(), "l", &position) == FAILURE) {
        return;
    }

    if (!aht) {
        php_error_docref(NULL, E_NOTICE, "Array was modified outside object and is no longer an array");
        return;
    }

    opos = position;

    if (position >= 0) { /* negative values are not supported */
        spl_array_rewind(intern);
        result = SUCCESS;

        while (position-- > 0 && (result = spl_array_next(intern)) == SUCCESS);

        if (result == SUCCESS && zend_hash_has_more_elements_ex(aht, spl_array_get_pos_ptr(aht, intern)) == SUCCESS) {
            return; /* ok */
        }
    }
    zend_throw_exception_ex(spl_ce_OutOfBoundsException, 0, "Seek position %pd is out of range", opos);
} /* }}} */

所以看起来没有办法在不循环遍历数组的情况下将数组指针设置到某个位置