How can i parse the number from the string each time automatic ?

Question

I have this two lines:
last_file = fi[fi.Length - 1].FullName;
string lastFileNumber = last_file.Substring(86, 6);
In last_file i have: C:\\Users\\chocolade1972\\AppData\\Local\\mws\\My Weather Station\\radar_temp_directory\\radar000142.gif
So i counted and found that the number in this case 000124 is starting from index 86 and length 6
But for example on my brother pc the directory is shorter the name is not chocolade1972 so the index is incorrect.
It's not 86.
How can i use the Substring to find the correct index every time on any pc that have a differenet directory length ?
In this case it's working fine on my pc for any image i can get the number no problems. But i want it to work also on other pc's.

Answer 1

You can use Regex to match the filename you want. 
Like Giovhan suggested you can first get the filename like:
string result;
result = Path.GetFileName(fileName);// in your example result = radar000142// in my regex I assume that a file can have a number of digits between 5 to 7 digits.Regex filenameRegex = new Regex("\d{5,7}");string number = filenameRegex.Match(result).Value;// by that way you can retrieve all numbers between 5 to 7 digits regardless of filename whether contains all 6 digits// or file that may contain 5 or 7 digits // You can play with the Regex code to decrease or increase number of digits by changing the numbers