retrieve all possible substring matches with n characters from a string

Question

Basically I want to retrieve all possible substring matches with n characters from a string, Here's my initial code but it only returns 2 matches.

String input = "abc12345abcd";
Regex  regex = new Regex(@"[A-Za-z]{3}"); //this will only return 2 matches
MatchCollection  matches = regex.Matches(input);

How should I get the following matches using regex?

abc
abc
bcd

Is this possible, if not will LINQ help this?

Thanks,

Answer 1

This sounds like a similar question to this.

Answer 2

String input = "abc12345abcd";
Regex regex = new Regex(@"[A-Za-z]{3}");
int i=0;
while(i<input.Length){
    Match m=regex.Match(input,i);
    if(m.Success){
     Console.WriteLine(m.Value);
     i=m.Index+1; //just increment one char, instead of length of match string
    }else break;
}

Results

abc
abc
bcd

Answer 3

I believe that, while not clearly documented, Matches returns non-overlapping matches -- so the second match for abc means there's nothing returned for bcd, as it would be overlapping.

To get overlapping matches, you can program a loop calling the Match (singular) method to get one match object at a time; as long as the match object has the Success property as true, you keep looping with the second argument to the Match method being one more than the Index property of the previous match object (to get the next match whether overlapping or not).