# Difference between Char.IsDigit() and Char.IsNumber() in C#

### Question

What's the difference between `Char.IsDigit()` and `Char.IsNumber()` in C#?

1
139
2/26/2013 9:37:26 AM

`Char.IsDigit()` is a subset of `Char.IsNumber()`.

Some of the characters that are 'numeric' but not digits include 0x00b2 and 0x00b3 which are superscripted 2 and 3 ('²' and '³') and the glyphs that are fractions such as '¼', '½', and '¾'.

Note that there are quite a few characters that `IsDigit()` returns `true` for that are not in the ASCII range of 0x30 to 0x39, such as these Thai digit characters: '๐' '๑' '๒' '๓' '๔' '๕' '๖' '๗' '๘' '๙'.

This snippet of code tells you which code points differ:

``````static private void test()
{
for (int i = 0; i <= 0xffff; ++i)
{
char c = (char) i;

if (Char.IsDigit( c) != Char.IsNumber( c)) {
Console.WriteLine( "Char value {0:x} IsDigit() = {1}, IsNumber() = {2}", i, Char.IsDigit( c), Char.IsNumber( c));
}
}
}
``````
141
12/12/2013 5:01:04 AM

Char.IsNumber() determines if a Char is of any numeric Unicode category. This contrasts with IsDigit, which determines if a Char is a radix-10 digit.

Valid numbers are members of the following categories in UnicodeCategory:

1. `DecimalDigitNumber`
Decimal digit character, that is, a character in the range 0 through 9. Signified by the Unicode designation "Nd" (number, decimal digit). The value is 8.
2. `LetterNumber`
Number represented by a letter, instead of a decimal digit, for example, the Roman numeral for five, which is "V". The indicator is signified by the Unicode designation "Nl" (number, letter). The value is 9.
3. `OtherNumber`
Number that is neither a decimal digit nor a letter number, for example, the fraction ½. The indicator is signified by the Unicode designation "No" (number, other). The value is 10.

## Conclusion

• `Char.IsDigit`:
Valid digits are members of the `DecimalDigitNumber` category only.
• `Char.IsNumber`:
Valid numbers are members of the `DecimalDigitNumber`, `LetterNumber`, or `OtherNumber` category.