In C#, how can I detect if a character is a non-ASCII character?

Question

I would like to check, in C#, if a char contains a non-ASCII character. What is the best way to check for special characters such as 志 or Ω?

http://social.msdn.microsoft.com/Forums/vstudio/en-US/bcdfb967-aa97-4d26-9daa-d20829f805b9/detect-nonascii-characters — Zaki, Sep 03 '13 at 15:39
you can also use regex http://stackoverflow.com/questions/123336/how-can-you-strip-non-ascii-characters-from-a-string-in-c — Zaki, Sep 03 '13 at 15:40

score 50 · Accepted Answer · answered Sep 03 '13 at 15:40

50

ASCII ranges from 0 - 127, so just check for that range:

char c = 'a';//or whatever char you have
bool isAscii = c < 128;

answered Sep 03 '13 at 15:40

musefan

17

And for those who want to be fancy, `bool isAscii = c <= sbyte.MaxValue;`. – Jeppe Stig Nielsen Sep 03 '13 at 16:57

score 49 · Answer 2 · edited Oct 30 '21 at 09:58

49

bool HasNonASCIIChars(string str)
{
    return (System.Text.Encoding.UTF8.GetByteCount(str) != str.Length);
}

edited Oct 30 '21 at 09:58

Wai Ha Lee

answered Oct 09 '19 at 13:23

Malik Khalil

3

Now that's an interesting way to go about this. Really clever! – Vesk May 22 '21 at 15:38

score 9 · Answer 3 · answered Dec 14 '22 at 10:17

Just in case anybody comes across this. In dotNET6 there is a new method to check whether a character is an ASCII character or not

public static bool IsAscii (char c);

To solve the issue, you can just write

var containsOnlyAscii = str.All(char.IsAscii);

using the LINQ All method.

In general, you can use this new method to check individual characters

var isAscii = char.IsAscii(c);

3 Answers3