Hi Gregory,

I haven't yet installed VS. Plan to do this later this week.

BTW, how should I test the code, what type of project should I chose?

Thanks again.

>>Thanks, Greg. I'll review the code this weekend.
>>
>Nadya,
>
>Version 3 - for lunch
>
>Mods
>- added null checking for parameters
>- fast mode detection
> if none of the chars in the 'from' occur in the 'to' a straight Replace() can be done
> otherwise it's the long loop
>
>If you find any bugs - please let me know
>
>

>// string
>namespace GregoryAdam.Base.ExtensionMethods
>{
>	public static partial class ExtensionMethods
>	{
>#region ChrTran
>		public static string ChrTran(this string s, string from, string to)
>		{
>			// check parameters
>			if( String.IsNullOrEmpty(s) )
>				return s;
>
>			if( String.IsNullOrEmpty(from) )
>				return s;
>
>	
>			// (1) Split from into translate and remove
>
>			// "1234", "56"
>			// translate = "12"
>			// remove = "34"
>			char[] translate, remove;
>
>			// "1234", ""
>			if (String.IsNullOrEmpty(to))
>			{
>				translate = new char[0];
>
>			}
>				// "1234", "5678"
>				// "1234", "56"
>				// "1234", "A"
>				// "1234", "567890"  - can happen
>			else
>			{
>				translate = new char[Math.Min(from.Length, to.Length)];
>				from.CopyTo(0, translate, 0, translate.Length);
>			}
>
>			remove = new char[from.Length - translate.Length];
>			from.CopyTo(translate.Length, remove, 0, remove.Length);
>
>			// (2) remove chars from s - but not those that will be translated
>			//	avoid	StrTran("AA", "B")
>			//			translate = "A", to = "B"
>			//			remove = "A"
>			var sb = new StringBuilder(s, s.Length);
>			int i, j;
>
>			for (i = remove.Length; --i >= 0; )
>			{
>				if( !translate.Contains( remove[i] ) )
>					sb.Replace(remove[i].ToString(), null);
>			}
>
>			// (3) translate
>
>			// if no char in from is in to, then a fast translate can be done
>			//  if not, we'll have to loop
>
>			if (translate.Length > 0)
>			{
>				bool fastTranslate = true;
>
>				for (i = translate.Length; --i >= 0; )
>				{
>					if (to.Contains(from[i]))
>					{
>						fastTranslate = false;
>						break;
>					}
>				}
>
>				if (fastTranslate)
>				{
>					for (i = translate.Length; --i >= 0; )
>					{
>						sb.Replace(translate[i], to[i]);
>					}
>				}
>				else
>				{
>					for (i = sb.Length; --i >= 0; )
>					{
>						if ((j = Array.IndexOf<char>(translate, sb[i])) >= 0)
>							sb[i] = to[j];
>					}
>				}
>			}
>			return sb.ToString();
>		}
>#if ChrTran_TESTSUITE
>		static string[,] chrtranTest = 
>			{	{ "AB", "AB", "BC", "BC" } ,
>				{ "AB", "AB", "B",	"B" },
>				{ "0123456", "45", null, "01236"},
>				{ "0123456", "456", "78", "012378"},
>				{ "01234567890", "456", "", "01237890"},
>				{ "02468", "02468", "1357", "1357"},
>				{ "02468", "02468", "1358", "1358" }
>			};
>
>		public static void chrtran_Test()
>		{
>			string s;
>
>			for (int i = -1; ++i <= chrtranTest.GetUpperBound(0); )
>			{
>				s = chrtranTest[i, 0].ChrTran(chrtranTest[i, 1], chrtranTest[i, 2]);
>
>				Console.WriteLine("{0},{1},{2} >> {3} {4} : {5}",
>								chrtranTest[i, 0],
>								chrtranTest[i, 1],
>								chrtranTest[i, 2],
>								chrtranTest[i, 3],
>								s,
>								s == chrtranTest[i, 3]
>							);
>			}
>		}
>#endif
>#endregion
>
>	}
>}
>