Regular expression for single quotes and double quotes

goli nagaraju

15y17.4kAzure

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

please reply the answer to my question.

Thank you,
G. Nagaraju

2 Replies

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Vulpes15y ago
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-_/.#$%^*()}{:;+=|!,?~@&<>' ]*"; // no double quotes
string allowed2 = @"[a-zA-Z0-9-_/.#$%^*()}{:;+=|!,?~@&<>"" ]*"; // 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
Vulpes15y ago
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-_/.#$%^*()}{:;+=|!,?~@&<>'"" ]*$"; // allow for either or both
bool b = Regex.IsMatch(text, r); // true