Need to cut multiple strings from between 2 others in a textbox

MIke Lumley

Hi All,
I have some code as follows:

string str = txtHTML2.Text;

int start = str.IndexOf("first") /*+ "first".Length*/;

int finish = str.LastIndexOf("last");

string str2 = str.Substring(start,finish - start);

listBox1.Items.Add(str2);

This copys the first ocurance between first\last to a listbox, what I need to do is to iterate through the whole textbox to the end because there is more to cut

Is there a way to do this? am I on the right path

any pointer to articales would be great

thanks in advance

Mike

5 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes14y ago
Accepted answer
If the TextBox contained this string:

The first and the last of the month

then your code would extract the following string (followed by a space) and add it to the ListBox:

first and the

If you had multiple occurrences of 'first' and 'last' in the same string, then the easiest way to extract all of them would be using a regular expression:

using System.Text.RegularExpressions;

// ...

string str = txtHTML2.Text;
MatchCollection matches = Regex.Matches(str, @"first.*?(?=last)");
foreach(Match m in matches) listBox1.Items.Add(m.Value);
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Vulpes14y ago
I'd start with this article which, despite its title, is quite comprehensive:

http://www.codeproject.com/Articles/9099/The-30-Minute-Regex-Tutorial
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MIke Lumley14y ago
Hi Vulpes
That WORKED a treat
Thankyou
Thankyou
Thankyou
Thankyou
Words cannot express how much!!
YOU are 1 TOP Coder
I've got to study this Regex because I'm going to need more can point me in the best plase to start
Thankyou once again Vulpes

Mike
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Vulpes14y ago
It's notoriously difficult to parse HTML using regular expressions but try the following:

string str = txtHTML2.Text;
string regExp = "(?s)(?<=).*?(?=£)";
MatchCollection matches = Regex.Matches(str, regExp);
foreach(Match m in matches) listBox1.Items.Add(m.Value);
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MIke Lumley14y ago
Hi Vulpes thanks agian for a speedy reply
I've tried your code, runs with no errors but nothing goes in listbox.
When I set breakpoint on first line, the "txtHTML" has text then "str" has same value,
but looking at "matches" stays with a value of "null" even on the exit of the method.
I've gone back to my original code and sent string to a textbox and it get nearly all the
original HTML. I've used this to get narrow down the block of HTML that I need, so getting there slowly.

            int start = str.IndexOf("") + "".Length;
            int finish = str.LastIndexOf("£");
            string str2 = str.Substring(start, finish - start);
            textBox1.Text = str2;
Just been looking at Regex wow what a topic.
Nice explanation of i++

Thanks Vulpes.

Mike
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