I have seen lots of questions on Stack Overflow where String.Compare is used to compare strings if one needs case insensitive comparison. I have even seen production code using the same method. I guess the usage is due to most of the developers having c/c++ background and used to methods like strcmpi.
string str1 = "TEST"; string str2 = "test"; bool caseInsensitiveEqual = String.Compare(str1, str2, StringComparison.InvariantCultureIgnoreCase) == 0;
is often found and considered a usual practice when it comes to case insensitive string comparison.
Another way is converting both of the parameters to either upper or lower case and then doing the comparison like:
string str1 = "TEST"; string str2 = "test"; bool caseInsensitiveEqual = str1.ToUpper() == str2.ToUpper();
Both of these approaches would work for most of the time, but there are issues:
- String.Compare is used for determining position in sort order (which string is bigger than other)
- Using ToUpper or ToLower could case incorrect results for strings in different cultures. (The Turkish İ Problem and Why You Should Care)
Use the framework provided String.Equals group of methods.
string str1 = "TEST"; string str2 = "test"; bool caseInsensitiveEqual = String.Equals(str1, str2, StringComparison.InvariantCultureIgnoreCase);
It has overloads to specify string comparison approaches using StringComparison Enumeration