Mega Code Archive
0641 Using RegexOptions
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The RegexOptions flags enum lets you tweak matching behavior.
A common use for RegexOptions is to perform a case-insensitive search:
using System;
using System.Text.RegularExpressions;
class Program
{
static void Main(string[] args)
{
Console.WriteLine(Regex.Match("a", "A", RegexOptions.IgnoreCase));
}
}
The output:
a
Most of the RegexOptions flags can be activated within a regular expression itself, using a single-letter code as follows:
using System;
using System.Text.RegularExpressions;
class Program
{
static void Main(string[] args)
{
Console.WriteLine(Regex.Match("a", @"(?i)A"));
}
}
The output:
a
You can turn options on and off throughout an expression as follows:
using System;
using System.Text.RegularExpressions;
class Program
{
static void Main(string[] args)
{
Console.WriteLine(Regex.Match("AAAa", @"(?i)a(?-i)a"));
}
}
The output:
Aa
Regular expression options and Regular expressions code
RegexOptions Enum value Regular expressions code
IgnoreCase i
Multiline m
ExplicitCapture n
Compiled c
Singleline s
IgnorePattern Whitespace x
RightToLeft r
ECMAScript N/A
CultureInvariant N/A
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