Question

I recently had to perform some string replacements in .net and found myself developing a regular expression replacement function for this purpose. After getting it to work I couldn’t help but think there must be a built in case insensitive replacement operation in .Net that I’m missing?

Surely when there are so many other string operations that support case insensitive comparission such as;

var compareStrings  = String.Compare("a", "b", blIgnoreCase);
var equalStrings    = String.Equals("a", "b", StringComparison.CurrentCultureIgnoreCase);

then there must be a built in equivalent for replace?

Answer 1

Found one in the comments here: http://www.codeproject.com/Messages/1835929/this-one-is-even-faster-and-more-flexible-modified.aspx

static public string Replace(string original, string pattern, string replacement, StringComparison comparisonType)
{
     return Replace(original, pattern, replacement, comparisonType, -1);
}

static public string Replace(string original, string pattern, string replacement, StringComparison comparisonType, int stringBuilderInitialSize)
{
     if (original == null)
     {
         return null;
     }

     if (String.IsNullOrEmpty(pattern))
     {
         return original;
     }


     int posCurrent = 0;
     int lenPattern = pattern.Length;
     int idxNext = original.IndexOf(pattern, comparisonType);
     StringBuilder result = new StringBuilder(stringBuilderInitialSize < 0 ? Math.Min(4096, original.Length) : stringBuilderInitialSize);

     while (idxNext >= 0)
     {
        result.Append(original, posCurrent, idxNext - posCurrent);
        result.Append(replacement);

        posCurrent = idxNext + lenPattern;

        idxNext = original.IndexOf(pattern, posCurrent, comparisonType);
      }

      result.Append(original, posCurrent, original.Length - posCurrent);

      return result.ToString();
}

Should be the fastest, but i haven’t checked.

Otherwise you should do what Simon suggested and use the VisualBasic Replace function. This is what i often do because of its case-insensitive capabilities.

string s = "SoftWare";
s = Microsoft.VisualBasic.Strings.Replace(s, "software", "hardware", 1, -1, Constants.vbTextCompare);

You have to add a reference to the Microsoft.VisualBasic dll.