Comparing two strings, ignoring case in C#
Solution 1
The first one is the correct one, and IMHO the more efficient one, since the second 'solution' instantiates a new string instance.
Solution 2
If you're looking for efficiency, use this:
string.Equals(val, "astringvalue", StringComparison.OrdinalIgnoreCase)
Ordinal comparisons can be significantly faster than culture-aware comparisons.
ToLowerCase
can be the better option if you're doing a lot of comparisons against the same string, however.
As with any performance optimization: measure it, then decide!
Solution 3
The .ToLowerCase
version is not going to be faster - it involves an extra string allocation
(which must later be collected), etc.
Personally, I'd use
string.Equals(val, "astringvalue", StringComparison.OrdinalIgnoreCase)
this avoids all the issues of culture-sensitive strings, but as a consequence it avoids all the issues of culture-sensitive strings. Only you know whether that is OK in your context.
Using the string.Equals
static method avoids any issues with val
being null
.
Solution 4
My general answer to this kind of question on "efficiency" is almost always, which ever version of the code is most readable, is the most efficient.
That being said, I think (val.ToLowerCase() == "astringvalue")
is pretty understandable at a glance by most people.
The efficience I refer to is not necesseraly in the execution of the code but rather in the maintanance and generally readability of the code in question.
Solution 5
I'd venture that the safest is to use String.Equals
to mitigate against the possibility that val is null
.
pwmusic
Updated on January 31, 2020Comments
-
pwmusic over 4 years
Which of the following two is more efficient? (Or maybe is there a third option that's better still?)
string val = "AStringValue"; if (val.Equals("astringvalue", StringComparison.InvariantCultureIgnoreCase))
OR
if (val.ToLowerCase() == "astringvalue")
?