regex - Perl: Replacing a string containing a question mark

Question

This is my code:

$html = 'Is this a question? Maybe.';
$old = 'question?';
$new = 'reply?';

$html =~ s/$old/$new/g;
print $html; exit;

Output is:

Is this a reply?? Maybe.

Desired ouput:

Is this a reply? Maybe.

What am I doing wrong? Thank you.

score 9 · Accepted Answer

使用quotemeta转义?：

$html = 'Is this a question? Maybe.';
$old = quotemeta 'question?';
$new = 'reply?';

$html =~ s/$old/$new/g;
print $html; exit;

score 6 · Accepted Answer

在正则表达式中，问号是表示one 或 none的运算符。因此，我们必须逃避它：

s/question\?/reply?/g

请注意，它在字符串中并不特殊。因为将随机字符串内插到正则表达式中可能会产生这种不良影响，所以您应该quotemeta首先使用它们。

score 2 · Accepted Answer

?在正则表达式中有特殊含义。你只需要在你的模式中转义它：

$old = 'question\?';

3 回答 3