Issue with regular expression

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Hello,

I have an issue in regular expression matching...

C#

string x = "user = 'sa' password='eX65dere' server = 'localhost'";
Regex rx = new Regex("password=\'([a-zA-Z0-9]\\_+)\'");
var r = rx.Match(x);
            if (r.Groups.Count > 0)
            {
                var g1 = r.Groups[0]; 
                label1.Text = g1.ToString();
            }

while executing this, I have got the following error message. parsing "password='([a-zA-Z0-9]\_+)'" - Unrecognized escape sequence \_. Can anyone help me on this?

Thanks
Sebastian

Posted 22-Mar-12 2:40am

Sebastian T Xavier

Updated 22-Mar-12 2:41am

v2

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3 solutions

Solution 2

How we can match _ in a regular expression?

Posted 22-Mar-12 18:37pm

Sebastian T Xavier

Solution 1

if you want \ to be part of regex then you will have to escape itself so instead of \ write \\ and you will be fine. [since \ is escape character.]

or do it like:

C#

Regex rx = new Regex(@"password='([a-zA-Z0-9]\_+)\'");

Posted 22-Mar-12 2:41am

Rahul Rajat Singh

Updated 22-Mar-12 2:42am

v2

Comments

Sebastian T Xavier 22-Mar-12 8:43am

Regex rx = new Regex("password=\'([a-zA-Z0-9]+)\'"); will works fine... And it will match for all small caps , large caps & numbers. Now I have added \\_ to match the _ , then it throws this error....so How I can escape this?

Sebastian T Xavier 22-Mar-12 8:45am

Like this what shall i do to match ' and " . How I can escape these two.

Rahul Rajat Singh 22-Mar-12 8:46am

see the edited portion. use the @ to take strings literally and avoind using escape characters.

Sebastian T Xavier 22-Mar-12 8:48am

That also have the same issue...

Rahul Rajat Singh 22-Mar-12 8:50am

but why are you trying to ecsape _ use this

Regex rx = new Regex(@"password='([a-zA-Z0-9]_+)\'");

Sebastian T Xavier 22-Mar-12 8:58am

this won't throw any error, but it is not giving me the desired output.

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Sebastian T Xavier · Accepted Answer · 2012-03-22T18:46:00

I have solved this by changing the expression as follows...

C#

Regex rx = new Regex(@"password='([a-zA-Z0-9\\%^&_*]+)\'");

--------------

again i have another question... Here is my updated expression...

C#

string x = "user = 'sa' password='e X65dere!@#$%^&*()' server = 'localhost'";
Regex rx = new Regex(@"password=\'([a-zA-Z0-9\\!@#$%^&*|() _'""*-+{}<>,.;/?:~`\[\]\\\\]+)\'");
    var r = rx.Match(x);
    if (r.Groups.Count > 0)
       {
          var g1 = r.Groups[0];
          MessageBox.Show(g1.ToString());
       }

In this case it will match for every small & large cap letters, numbers and special characters except = . If the password contains = the expression fails... can you please help?

Regards
Sebastian