String searching

[Techno]

ok, even though we all should know string searching should be avoided where possible, this cannot unfortunately.

say we have these sets of strings:

temporary
permenant
temporary/permenant
contract
contract/temporary


and we are testing with a string called "perm".

how can I check to see if each one them contains that word? The complication is this:

permenant and temporary/permenant SHOULD evaluate to true, since "temporary/permenant" contains the word "perm"




I am using .NET 1.1 here for this project.

[Atheist]

The Contains method would be suitable in this case, but since that is a new method in the .Net 2.0 framework, you could use the IndexOf method

string hey = "hello";
                hey.IndexOf("e"); //will return 1, because e exists on index 1 in the string.

If IndexOf returns -1, the substring doesnt exist within the string.

[corwin_ranger]

You'll want to use the String.Contains() method. It's not static, so you'll need to do something like what's below. You can obviously do something more efficient based on your needs. I also included to the .ToLower() method since you may not know if your test string is all upper or lower case.

using System;
using System.Collections.Generic;
using System.Text;

namespace ConsoleApplication1
{
	class Program
	{
		static void Main(string[] args)
		{
			string a = "temporary";
			string b = "permenant";
			string c = "temporary/permenant";
			string d = "contract";
			string e = "contract/temporary";
			string test = "perm";

			if (a.ToLower().Contains(test))
			{
				Console.WriteLine("Yes");
			}

			else
			{
				Console.WriteLine("No");
			}

			if (b.ToLower().Contains(test))
			{
				Console.WriteLine("Yes");
			}

			else
			{
				Console.WriteLine("No");
			}

			if (c.ToLower().Contains(test))
			{
				Console.WriteLine("Yes");
			}

			else
			{
				Console.WriteLine("No");
			}

			if (d.ToLower().Contains(test))
			{
				Console.WriteLine("Yes");
			}

			else
			{
				Console.WriteLine("No");
			}

			if (e.ToLower().Contains(test))
			{
				Console.WriteLine("Yes");
			}

			else
			{
				Console.WriteLine("No");
			}

			Console.ReadLine();
		}
	}
}

[Techno]

.NET 1.1 does not have the contains method. however I did find a solution.

simply did a .Split() on the string then went through each item in the array, got the first 4 characters and did a comparison (indexof) with the other string which had 4 characters - seems to work just fine, thankfully

[wossname]

Split is one of the most appallingly slow functions in the whole .net library.

If you are really interested in optimisation, learn how to use pointers and develop a custom algorithm to suit your exact requirement for this task. It will be much more efficient and won't double your memory usage (like Split will).

[Techno]

sure. i understand and am aware of this but apperently they dont care about performance....typical.
but yeh

[wossname]

Too few people do these days.

[Jumpercables]

You could use Regular Expressions.

Regex regex = new Regex("perm", RegexOptions.IgnoreCase);

            Console.WriteLine(regex.IsMatch("temporary"));
            Console.WriteLine(regex.IsMatch("permenant"));
            Console.WriteLine(regex.IsMatch("temporary/permenant"));

[Techno]

could do but as well as it being expensive, it is the right method to use however I guess I need a regex expression to look for the criterias:

temp/perm
permenant
perm/temp


so it needs to look for "perm" and bring back temp/perm, permenant and perm/temp