Regex confusion

[Tom Jones]

Hi,

I cannot seem to figure out how to construct a regex for what I need.

I need to match:

a

or

a.a.a.a // note: there can be any number of ".a" repetitions

or

a.*

or

a.a.a.a.*

where 'a' can be "one or more contiguous alpha chars".

The optional repetition is throwing me...

Any pointers are appreciated...

Thanks,
Tom

[Tom Jones]

"Tom Jones" <to********@hotmail.com> wrote in message
news:ux**************@tk2msftngp13.phx.gbl...

Hi,

I cannot seem to figure out how to construct a regex for what I need.

I need to match:

a

or

a.a.a.a // note: there can be any number of ".a" repetitions

or

a.*

or

a.a.a.a.*

where 'a' can be "one or more contiguous alpha chars".

The optional repetition is throwing me...

Does anyone see a problem with this: ^a(?:$|(?:\.a)*(?:\.\*)?)$

That seems to work but I don't know if I am missing something...

Tom

[Chua Wen Ching]

Hi Tom Jones,

I assume you want to get every "a." Try to do this:

A short example.

Codes:

using System;
using System.Text.RegularExpressions;

class RegEx
{
public static void Main()
{
MatchCollection mCollect;
String[] results = new String[20];
int[] mPosition = new int[20];

Regex r = new Regex("a.");
mCollect = r.Matches("a.c.a.a.a.a.a.a.f.g.g.ggg.c.a.");
for (int i = 0; i < mCollect.Count; i++)
{
results[i] = mCollect[i].Value;
Console.WriteLine(results[i]);
mPosition[i] = mCollect[i].Index;
Console.WriteLine(mPosition[i]);
}
}
}

Hope it helps. Correct me if i am wrong.
--
Regards,
Chua Wen Ching :)
"Tom Jones" wrote:

Hi,

I cannot seem to figure out how to construct a regex for what I need.

I need to match:

a

or

a.a.a.a // note: there can be any number of ".a" repetitions

or

a.*

or

a.a.a.a.*

where 'a' can be "one or more contiguous alpha chars".

The optional repetition is throwing me...

Any pointers are appreciated...

Thanks,
Tom

[Niki Estner]

"Tom Jones" <to********@hotmail.com> wrote in
news:%2****************@tk2msftngp13.phx.gbl...

"Tom Jones" <to********@hotmail.com> wrote in message
news:ux**************@tk2msftngp13.phx.gbl...
...
Does anyone see a problem with this: ^a(?:$|(?:\.a)*(?:\.\*)?)$

I just entered this in expresso - seems to work fine. I don't think there is
a problem in that regex.

Niki