Can t escape the backslash with regex

Question

I m using the following regex    a-zA-Z0-9                     amp                      s -  1 1000     I know it s ugly  but so far it serves its purpose other than the backslash not being allowed as I think it should because it s escaped  I also tried    instead of     but same results  Any ideas

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This solution fixed my problem while replacing br tag to   n        alert content replace   lt br    gt  g   n

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If you re putting this in a string within a program  you may actually need to use four backslashes  because the string parser will remove two of them when  de-escaping  it for the string  and then the regex needs two for an escaped regex backslash    For instance   regex           is interpreted as     regex       escaped backslash  followed by       escaped backslash     is interpreted as     regex       is interpreted as a regex that matches a single backslash     Depending on the language  you might be able to use a different form of quoting that doesn t parse escape sequences to avoid having to use as many - for instance  in Python   re compile r        The r in front of the quotes makes it a raw string which doesn t parse backslash escapes

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From http   www regular-expressions info charclass html    Note that the only special characters or metacharacters inside a character class are the closing bracket      the backslash       the caret     and the hyphen  -   The usual metacharacters are normal characters inside a character class  and do not need to be escaped by a backslash  To search for a star or plus  use       Your regex will work fine if you escape the regular metacharacters inside a character class  but doing so significantly reduces readability  To include a backslash as a character without any special meaning inside a character class  you have to escape it with another backslash     x  matches a backslash or an x  The closing bracket      the caret     and the hyphen  -  can be included by escaping them with a backslash  or by placing them in a position where they do not take on their special meaning  I recommend the latter method  since it improves readability  To include a caret  place it anywhere except right after the opening bracket   x   matches an x or a caret  You can put the closing bracket right after the opening bracket  or the negating caret    x  matches a closing bracket or an x     x  matches any character that is not a closing bracket or an x  The hyphen can be included right after the opening bracket  or right before the closing bracket  or right after the negating caret  Both  -x  and  x-  match an x or a hyphen   What language are you writing the regex in

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you can use   at the end to skip one  quot   quot  regex  quot       quot

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The backslash   is the escape character for regular expressions  Therefore a double backslash would indeed mean a single  literal backslash      backslash  followed by any of               escapes the special character to suppress its special meaning   ref   http   www regular-expressions info reference html

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If it s not a literal  you have to use      so that you get    which means an escaped backslash   That s because there are two representations  In the string representation of your regex  you have         Which is what gets sent to the parser  The parser will see    which it interprets as a valid escaped-backslash  which matches a single backslash

[regex] Can't escape the backslash with regex?

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