Character sets act as wildcards for a particular set of characters.
| Expression | Meaning | Inverse ("not") |
|---|---|---|
| [abcdef] | Matches a single character in the list | [^abcdef] |
| [a-f] | Matches a single character in a range | [^a-f] |
| \d | Matches a decimal digit Same as [0–9] | \D |
| \w | Matches a word character | \W |
| \s | Matches a whitespace character Same as [\n\r\t\f] | \S |
| \p{category} | Matches a character in a specified category | \P |
| . | (Default mode) Matches any character except \n | \n |
| . | (SingleLine mode) Matches any character | \n |
Character categories
| Quantifier | Meaning |
|---|---|
| \p{L} | Letters |
| \p{Lu} | Uppercase letters |
| \p{Ll} | Lowercase letters |
| \p{N} | Numbers |
| \p{P} | Punctuation |
| \p{M} | Diacritic marks |
| \p{S} | Symbols |
| \p{Z} | Separators |
| \p{C} | Control characters |
To match exactly one of a set of characters, put the character set in square brackets:
using System;
using System.Text.RegularExpressions;
class Program
{
static void Main(string[] args)
{
Console.Write(Regex.Matches("That demo is that demo.", "[Tt]hat").Count);
}
}
The output:
2
To match any character except those in a set, put the set in square brackets with a ^ symbol before the first character:
using System;
using System.Text.RegularExpressions;
class Program
{
static void Main(string[] args)
{
Console.Write(Regex.Match("quiz quest", "q[^aeiou]").Index);
}
}
The output:
0
You can specify a range of characters with a hyphen.
The following regular expression captures a chess move:
using System;
using System.Text.RegularExpressions;
class Program
{
static void Main(string[] args)
{
Console.Write(Regex.Match("b1-c4", @"[a-h]\d-[a-h]\d").Success);
}
}
The output:
True
using System;
using System.Text.RegularExpressions;
class Program
{
static void Main(string[] args)
{
Console.Write(Regex.IsMatch("Yes, please", @"\p{P}"));
}
}
The output:
True
We will find more uses for \d, \w, and . when we combine them with quantifiers.
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