foreach访问索引或者关联数组

时间:2020-03-05 18:54:57  来源:igfitidea点击:

我有以下代码片段。

$items['A'] = "Test";
$items['B'] = "Test";
$items['C'] = "Test";
$items['D'] = "Test";

$index = 0;
foreach($items as $key => $value)
{
    echo "$index is a $key containing $value\n";
    $index++;
}

预期产量:

0 is a A containing Test
1 is a B containing Test
2 is a C containing Test
3 is a D containing Test

有没有办法忽略$ index变量?

解决方案

回答

$ index变量存在某种误导性。该数字不是索引," A"," B"," C"," D"键是索引。我们仍然可以通过编号索引$ index [1]访问数据,但这并不是重点。如果我们真的想保留编号索引,我几乎会重新组织数据:

$items[] = array("A", "Test");
$items[] = array("B", "Test");
$items[] = array("C", "Test");
$items[] = array("D", "Test");

foreach($items as $key => $value) {
    echo $key.' is a '.$value[0].' containing '.$value[1];
}

回答

你可以这样做:

$items[A] = "Test";
$items[B] = "Test";
$items[C] = "Test";
$items[D] = "Test";

for($i=0;$i<count($items);$i++)
{
    list($key,$value) = each($items[$i]);
    echo "$i $key contains $value";
}

我以前没有做过,但是从理论上讲应该可以。

回答

请注意在此处定义键的方式。虽然示例有效,但可能并非总是如此:

$myArr = array();
$myArr[A] = "a";  // "A" is assumed.
echo $myArr['A']; // "a" - this is expected.

define ('A', 'aye');

$myArr2 = array();
$myArr2[A] = "a"; // A is a constant

echo $myArr['A']; // error, no key.
print_r($myArr);

// Array
// (
//     [aye] => a
// )