如何使用preg_replace在PHP中转义$？

Question

I am using preg_replace to escape special characters:

$tmpStr=preg_replace("/\?/", "\?", $tmpStr);
$tmpStr=preg_replace("/\#/", "\#", $tmpStr);
$tmpStr=preg_replace("/\^/", "\^", $tmpStr);
$tmpStr=preg_replace("/\&/", "\&", $tmpStr);
$tmpStr=preg_replace("/\*/", "\*", $tmpStr);
$tmpStr=preg_replace("/\(/", "\(", $tmpStr);
$tmpStr=preg_replace("/\)/", "\)", $tmpStr);
$tmpStr=preg_replace("/\//", "\/", $tmpStr); 

But I am not able to escape $ using the same function:

$tmpStr=preg_replace("/\$/", "\$", $tmpStr);

And also when I use the above statement all the spaces get replaced by $ and $ is not getting escaped.

How do I escape the dollar sign correctly?

Answer 1

我强烈建议使用preg_quote（）代替。

Answer 2

The correct answer is that you must escape the backslash and the dollar sign in the regex using PHP's escape characters.

backslash = \\
dollar sign = \$

$tmpStr=preg_replace("/\\\$/", "\\$", $tmpStr);

This is useful for anyone that needs to match a string that contains a dollar sign.

Answer 3

The $ sign has to be escaped with itself so

$tmpStr=preg_replace("/$$/", "\$", $tmpStr);

I would also advise to look to addslashes instead.

Answer 4

Looks like your problem is one of escaping. Single quotes ( ' ) in PHP work differently than double quotes ( " ). It's a lot like in Perl, where variable interpolation does not happen in singly-quoted strings, and the dollar sign ( $ ) is not a meta-character:

print "\$"; # prints $
print '\$'; # prints \$

Also, Perl's character classes will simplify your code:

$tmpStr = preg_replace('/([?#^&*()$\\/])/', '\\\\$1', $tmpStr);

Answer 5

Yes, it does seem that \\\\$ is seen by PHP as $ in a double-quoted string. That means you have to make PHP see a \\$ by saying \\\\\\$ .

I just tried preg_replace("/\\\\\\$$k\\\\\\$/", $v, $data) and indeed it works (replaces occurrences of $KEY$ with VALUE.

Answer 6

$pattern = preg_replace('/\$(.+)/', '\\\$$1', $pattern);

Answer 7

IIRC you replace $ with $. So it should be $$

You can also try

$tmpStr=preg_replace('/\$/', '\$', $tmpStr);

Answer 8

isn't it true that PHP sees \\$ as $ ? I haven't tested this out, it might go like this;

php is first, and replaces your "/\\$/" with "/$/" then the preg engine does it's magic .. unfortunately, $ is a regular expression operator ( I believe it matches the end of a string?), so it doesn't find the $-characters in your text but will

I think, what you need to do, is to doubble escape the $-character like so;

$tmpStr=preg_replace("/\\$/", "\\$", $tmpStr);

Also .. in this case, I would have just used str_replace()

Answer 9

在PHP中，对于HTML中使用的“$”的特定情况，您还可以为其实体执行先前的替换：

$tmpStr = str_replace('$', '$',$tmpStr);

Answer 10

Try a addslashes() ?

Check php.net / addslashes()