Making shortcuts for case-insensitive String.IndexOf

Extension methods in C# allow programmers to correct situations where .NET does not provide the easiest way to do things. Most of the times when I want to do a String.IndexOf, it is the case insensitive version I need. .NET defaults to the most sensitive version. In c# the following code is needed to perform such a call:

  if (str.IndexOf("test", StringComparison.OrdinalIgnoreCase) >= 0) {
    ...
  }

The extension methods for the IndexOf are called IndexOf_CI. They cannot be called IndexOf since the parameter signature is the same. Where CI stands for Case-Insensitive. Below I created the overloads for IndexOf the framework offers.

public static int IndexOf_CI(this String str, string value)
{
  return str.IndexOf(value, StringComparison.OrdinalIgnoreCase);
}

public static int IndexOf_CI(this String str, char value)
{
  return str.IndexOf(value.ToString(), StringComparison.OrdinalIgnoreCase);
}

public static int IndexOf_CI(this String str, string value, int startIndex)
{
  return str.IndexOf(value, startIndex, StringComparison.OrdinalIgnoreCase);
}

public static int IndexOf_CI(this String str, char value, int startIndex)
{
  return str.IndexOf(value.ToString(), startIndex, StringComparison.OrdinalIgnoreCase);
}

public static int IndexOf_CI(this String str, string value, int startIndex, int count)
{
  return str.IndexOf(value, startIndex, count, StringComparison.OrdinalIgnoreCase);
}

public static int IndexOf_CI(this String str, char value, int startIndex, int count)
{
  return str.IndexOf(value.ToString(), startIndex, count, StringComparison.OrdinalIgnoreCase);
}

The code becomes a lot shorter en more friendly to the eye:

  if (str.IndexOf_CI("test") >= 0) {
    ...
  }

To complete this library also the IndexOfAny and LastIndexOf need to be supplied with case-insensitive versions.

A System.String extension method Substring

Almost every time I use String.Substring() I have to do a few IndexOf calls to find the "startIndex" en "length" to use. This includes declaring local variables and verifying that the index found is not smaller than zero. This extension method solves these issues. (Long live C# 3.0!)

public static string Substring(this String str, string startText, string endText, StringComparison comparisonType)
{
  string lsResult = "";
  Int32 liStartPos = str.IndexOf(startText, comparisonType);
  if (liStartPos >= 0) {
    liStartPos = liStartPos + startText.Length;
    Int32 liEndPos = str.IndexOf(endText, liStartPos, comparisonType);
    if (liEndPos >= 0) {
      lsResult = str.Substring(liStartPos, liEndPos - liStartPos);
    }
  }
  return lsResult;
}

public static string Substring(this String str, string startText, string endText)
{
  string lsResult = "";
  Int32 liStartPos = str.IndexOf(startText, StringComparison.CurrentCulture);
  if (liStartPos >= 0) {
    liStartPos = liStartPos + startText.Length;
    Int32 liEndPos = str.IndexOf(endText, liStartPos, StringComparison.CurrentCulture);
    if (liEndPos >= 0) {
      lsResult = str.Substring(liStartPos, liEndPos - liStartPos);
    }
  }
  return lsResult;
}

I wasn't sure if overloading existing methods was alowed, but it works.