Regular expression for single quotes and double quotes

Question

single quotes and double quots both are allowed, so i am using regular expression but it is accepted either single quote or double quote but both are not allowed.
i am using following regular expression in asp.net

"^[a-zA-Z0-9-_/.#$%^*()}{:;+=|!,?~@&amp<>' ]*$"

please reply the answer to my question.

Thank you,
G. Nagaraju

Vulpes · Answer

For the second one the following - which uses negative look-ahead - should work: string text1 = @'abc123'; // single quotes only string text2 = @abc123; // double quotes only string text3 = @'abc123; // mixed quotes string text4 = @abc123'; // mixed quotes string allowed1 = @[a-zA-Z0-9-_/.#$%^*()}{:;+=|!?~@&amp ' ]*; // no double quotes string allowed2 = @[a-zA-Z0-9-_/.#$%^*()}{:;+=|!?~@&amp  ]*; // no single quotes string r = @^((?!.*) + allowed1 + |(?!.*') + allowed2 + )$; bool b1 = Regex.IsMatch(text1 r); // true bool b2 = Regex.IsMatch(text2 r); // true bool b3 = Regex.IsMatch(text3 r); // false bool b4 = Regex.IsMatch(text4 r); // false

Vulpes · Answer

Can you clarify whether you want to allow for: 1. Single quotes or double quotes or both 2. Single quotes or double quotes but not both. I'd need to think about the second one but the first one would be just a matter of doubling the double quotes and using a verbatim string: string text = @'; // includes single and double quotes string r = @^[a-zA-Z0-9-_/.#$%^*()}{:;+=|!?~@&amp ' ]*$; // allow for either or both bool b = Regex.IsMatch(text r); // true