How to use Regular Expression in .NET

[anonieko@hotmail.com]

Here is an example. For a time server which returns a time field
string, you can extract the time by the following code:




'VB.NET
Imports System.Text.Reg ularExpressions
'..
Dim s As String
Dim r As Regex
s = "Grennwich time 12:15pm September 1, 2001"
r = New Regex(".*(\d{2} :\d{2}[ap]m)", RegexOptions.Ig noreCase)
If r.Match(s).Succ ess Then
Console.Write(r .Match(s).Resul t("$1"))




// C#
using System.Text.Reg ularExpressions ;
//...
String s = "Grennwich time 12:15pm September 1, 2001";
Regex r = new Regex(".*(\d{2} :\d{2}[ap]m)", RegexOptions.Ig noreCase);

if ( r.Match(s).Succ ess)
{
Console.Write(r .Match(s).Resul t("$1"));
}

[Hans Kesting]

Re: How to use Regular Expression in .NET

> Here is an example. For a time server which returns a time field[color=blue]
> string, you can extract the time by the following code:
>
>
>
>
> 'VB.NET
> Imports System.Text.Reg ularExpressions
> '..
> Dim s As String
> Dim r As Regex
> s = "Grennwich time 12:15pm September 1, 2001"
> r = New Regex(".*(\d{2} :\d{2}[ap]m)", RegexOptions.Ig noreCase)
> If r.Match(s).Succ ess Then
> Console.Write(r .Match(s).Resul t("$1"))
>
>
>
>
> // C#
> using System.Text.Reg ularExpressions ;
> //...
> String s = "Grennwich time 12:15pm September 1, 2001";
> Regex r = new Regex(".*(\d{2} :\d{2}[ap]m)", RegexOptions.Ig noreCase);
>
> if ( r.Match(s).Succ ess)
> {
> Console.Write(r .Match(s).Resul t("$1"));
> }[/color]

Within C# strings a \ starts an "escape sequence". Use
new Regex(@".*(\d{2 }:\d{2}[ap]m)", ...

Hans Kesting

[Jay R. Wren]

Re: How to use Regular Expression in .NET

anonieko@hotmai l.com wrote:[color=blue]
> // C#
> using System.Text.Reg ularExpressions ;
> //...
> String s = "Grennwich time 12:15pm September 1, 2001";
> Regex r = new Regex(".*(\d{2} :\d{2}[ap]m)", RegexOptions.Ig noreCase);
>
> if ( r.Match(s).Succ ess)
> {
> Console.Write(r .Match(s).Resul t("$1"));
> }
>[/color]

I find your use of r.Match(s).Resu lt("$1") interesting. I didn't know
that one could use Match that way. Indeed I am not familiar with the
Result() member.

I typically use the Group() member and its Value property for extracting
data from the Match.

Does anyone know which is more efficient?

Regex.Match(inp utstring, "\s+(\d{2}:\d{2 }[ap]m)",
RegexOptions.Ig noreCase).Group (1).Value;

vs

Regex.Match(inp utstring, "\s+(\d{2}:\d{2 }[ap]m)",
RegexOptions.Ig noreCase).Resul t("$1");

--
Jay R. Wren