使用变量变量时未初始化的字符串偏移通知

Question

运行以下代码时，一切正常，直到 $i = 5。之后，我收到未初始化的字符串偏移通知，即使数组似乎已正确填充。我在本地运行时收到此通知，但在远程服务器上检查时却没有。两者都在运行 v5.2.11。我假设根据错误报告配置，本地和远程的输出不同，但是是什么导致了通知？

代码：

$i = 0;
$row = 0;
$col = 0;
$quad = 0;
while(count($ripDigits) > 0)
{
    $ranNum = rand(0, count($ripDigits) - 1);
    $ripDigit_splice = array_splice($ripDigits, $ranNum, 1);
    $ranDigit = $ripDigit_splice[0];
    echo ("\$i = " . $i . " | count(\$ripDigits) = " . count($ripDigits) . "<br />\n");

    $thisRow = "row_" . $row;
    $$thisRow[$i] = $ranDigit;

    echo ("\t\t<td><b>" . $$thisRow[$i] . "</b></td>\n");

    $thisUsedColumn = "usedDigits_column_" . $i;
    $$thisUsedColumn[$col] = $$thisRow[$i];

    $thisUsedColumn = "usedDigits_quad_" . $i;
    $$thisUsedColumn[$quad] = $$thisRow[$i];

    $i++;
}

输出：

$i = 0 | count($ripDigits) = 8
$i = 1 | count($ripDigits) = 7
$i = 2 | count($ripDigits) = 6
$i = 3 | count($ripDigits) = 5
$i = 4 | count($ripDigits) = 4
$i = 5 | count($ripDigits) = 3

Notice: Uninitialized string offset: 5 in script.php on line 97

Notice: Uninitialized string offset: 5 in script.php on line 99

Notice: Uninitialized string offset: 5 in script.php on line 102

Notice: Uninitialized string offset: 5 in script.php on line 105
$i = 6 | count($ripDigits) = 2

Notice: Uninitialized string offset: 6 in script.php on line 97

Notice: Uninitialized string offset: 6 in script.php on line 99

Notice: Uninitialized string offset: 6 in script.php on line 102

Notice: Uninitialized string offset: 6 in script.php on line 105
$i = 7 | count($ripDigits) = 1

Notice: Uninitialized string offset: 7 in script.php on line 97

Notice: Uninitialized string offset: 7 in script.php on line 99

Notice: Uninitialized string offset: 7 in script.php on line 102

Notice: Uninitialized string offset: 7 in script.php on line 105
$i = 8 | count($ripDigits) = 0

Notice: Uninitialized string offset: 8 in script.php on line 97

Notice: Uninitialized string offset: 8 in script.php on line 99

Notice: Uninitialized string offset: 8 in script.php on line 102

Notice: Uninitialized string offset: 8 in script.php on line 105

1   8   4   2   7   5   9   3   6

提前致谢！

Answer 1

我猜你的服务器和本地机器的 php 版本是不同的。今天我也收到了这个消息，如果你使用 xammp v.1.7.4 你会收到这个消息，但是如果你使用 1.7.3 你不会。

Answer 2

好的，我不太确定这样做的目的是什么，所以很难说……但我怀疑这将通过在变量变量中使用大括号来解决。它试图使用 $thisRow[$i] 作为变量名，但它不存在。

$i = 0;
$row = 0;
$col = 0;
$quad = 0;
while(count($ripDigits) > 0) {
    $ranNum = rand(0, count($ripDigits) - 1);
    $ripDigit_splice = array_splice($ripDigits, $ranNum, 1);
    $ranDigit = $ripDigit_splice[0];
    echo ("\$i = " . $i . " | count(\$ripDigits) = " . count($ripDigits) . "<br />\n");

    $thisRow = "row_" . $row;
    ${$thisRow}[$i] = $ranDigit;

    echo ("\t\t<td><b>" . ${$thisRow}[$i] . "</b></td>\n");

    $thisUsedColumn = "usedDigits_column_" . $i;
    ${$thisUsedColumn}[$col] = ${$thisRow}[$i];

    $thisUsedColumn = "usedDigits_quad_" . $i;
    ${$thisUsedColumn}[$quad] = ${$thisRow}[$i];

    $i++;
}

这适用于 ripDigits 被初始化为 6 个数字的数组。

另外，关于它为什么在服务器上“工作” - 可能的错误报告 (E_NOTICE) 刚刚关闭。