Regex Help

[Steve]

Hi,

I have an array of strings e.g. "one","two","three","four","fourteen"

From the following string "onethreefourteenten"

I would like to know that strings have been matched; strings
[0],[2],[4] but not [3].

What i'm trying to get is the longest word beginning at a particular
position, so the above example matches "fourteen" and not "four"

thanks,

 

[Daniel Bass]

A way to do this without Regex (if this is an option) is to do as follows:

----------------------

string szStringToSearch = "onethreefourteenten";
string szCurrentLongestMatch = "";

foreach ( string sz in StringsArray )
{
if ( szStringToSearch.IndexOf ( sz ) >= 0 )
{
if ( szCurrentLongestMatch.Length < sz.Length )
{
szCurrentLongestMatch = sz;
}
}
}

Console.WriteLine ( "The Longest Match is :" + szCurrentLongestMatch );

 

[Rahul Anand]

Hi Steve

The regular expression by default uses a *greedy* matching
algorithm i.e. it tries to match the longest possible
string.

So, if you specify the longer strings before in the regex
pattern the longer strings will be matched first.

For example i just tried with this code in C#:

[SNIP]


string s = "onethreefourteen";
string [] sar = {"one","two","three","four","fourteen"};
cmp cm = new cmp();
Array.Sort(sar,cm);
Regex r = new Regex(String.Join
("|",sar),RegexOptions.IgnoreCase);
Match m ;
for (m = r.Match(s); m.Success; m = m.NextMatch())
{
Console.WriteLine("Found " + m.Groups[0].Value + " at "
+ m.Groups[0].Index);
}


class cmp : IComparer
{
public Int32 Compare(Object x, Object y)
{
if(x.ToString().Length ==
y.ToString().Length)
return 0;
else if(x.ToString().Length >
y.ToString().Length)
return -1;
else
return 1;
}

}

[/SNIP]

As "fourteen" is longer than "four" so regex will match
only fourteen as it is specified before "four" in pattern.

Hope it will help.

--
Cheers,
Rahul Anand

-----Original Message-----
Hi,

I have an array of strings

e.g. "one","two","three","four","fourteen"

From the following string "onethreefourteenten"

I would like to know that strings have been matched; strings
[0],[2],[4] but not [3].

What i'm trying to get is the longest word beginning at a particular
position, so the above example matches "fourteen" and not "four"

thanks,
.