Question

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

Answer 1

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));         }     } }