extracting sustrings from a string to array

wajid ansari

Hi

I want to extract sustrings from a string and want to store in an array.
The string is dynamic it will change but the criteria to extract substring is same.
say for example a string str="something is [!better] than [!nothing]"
so i need to extract [!better] and [!nothing] from the string and store it in a string array, the string is dynamic it changes but i need to extract data between [ and ] including both the square brackets.
If anybody can send any sample code, I will be very thankfull.
Thanks

Ansari

4 Replies

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

Alan18y ago
Accepted answer
OK, here's a revised version which can deal with any number of substrings:

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        List list = new List();
        string str = "something is [!better] than [!nothing]";
        list.AddRange(ExtractSubstrings(str));
        string str2 = "something [!is] better [!than] [!nothing]";
        list.AddRange(ExtractSubstrings(str2));
        string[] results = list.ToArray();

        // check it worked
        foreach(string result in results)
        {
            Console.WriteLine(result);
        }
        Console.ReadKey();
    }

    static List ExtractSubstrings(string str)
    {
       if (str == null) return null;
       List results = new List();
       if (str == "") return results; // empty list
       int index1 = 0, index2 = 0;
       bool finished = false;

       do
       {
          index1 = str.IndexOf("[", index2);
          if (index1 == - 1)
          {
            finished = true;
          }
          else
          {
            index2 = str.IndexOf("]", index1);
            if (index2 == - 1)
            {
               finished = true;
            }
            else
            {
               results.Add(str.Substring(index1, index2 - index1 + 1));
            }
          }
        }
        while(!finished);

        return results;
    }

}
wajid ansari18y ago
Thanks a lot alan.
your code is very helpfull.
wajid ansari18y ago
Hi Alan
Thanks for your quick reply. I appreciate it your help.
One more updation in the code please, Your code seems to work to extract two substrings but if the string is "something [!is] better [!than] [!nothing]" then I need to extract three substrings but it is extracting [!is] and [!than], can you please update your code to get any number of substrings because the string that I am passing will have any number of substrings. Thanks again, Hope you will reply soon.
Thanks
Ansari
Alan18y ago
You could use regular expressions for this but I thought I'd do it using ordinary string parsing (including full error checking) which should be quicker:

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        List list = new List();
        string str = "something is [!better] than [!nothing]";
        string sub1, sub2;
        ExtractSubstrings(str, out sub1, out sub2);
        list.Add(sub1);
        list.Add(sub2);
        string str2 = "nothing is [!worse] than [!something]";
        string sub3, sub4;
        ExtractSubstrings(str2, out sub3, out sub4);
        list.Add(sub3);
        list.Add(sub4);
        string[] results = list.ToArray();

        // check it worked
        foreach(string result in results)
        {
            Console.WriteLine(result);
        }
        Console.ReadKey();
    }

    static void ExtractSubstrings(string str, out string sub1, out string sub2)
    {
       if (String.IsNullOrEmpty(str))
       {
           sub1 = sub2 = str;
           return;
       }
       int index1 = str.IndexOf("[");
       if (index1 == - 1)
       {
           sub1 = sub2 = "";
           return;
       }
       int index2 = str.IndexOf("]", index1);
       if (index2 == - 1)
       {
           sub1 = sub2 = "";
           return;
       }
       sub1 = str.Substring(index1, index2 - index1 + 1);
       int index3 = str.IndexOf("[", index2);
       if (index3 == - 1)
       {
           sub2 = "";
           return;
       }
       int index4 = str.IndexOf("]", index3);
       if (index4 == - 1)
       {
           sub2 = "";
           return;
       }
       sub2 = str.Substring(index3, index4 - index3 + 1);
    }

}