C# Language Common String Operations Getting x characters from the right side of a string
Example
Visual Basic has Left, Right, and Mid functions that returns characters from the Left, Right, and Middle of a string. These methods does not exist in C#, but can be implemented with Substring(). They can be implemented as an extension methods like the following:
public static class StringExtensions
{
/// <summary>
/// VB Left function
/// </summary>
/// <param name="stringparam"></param>
/// <param name="numchars"></param>
/// <returns>Left-most numchars characters</returns>
public static string Left( this string stringparam, int numchars )
{
// Handle possible Null or numeric stringparam being passed
stringparam += string.Empty;
// Handle possible negative numchars being passed
numchars = Math.Abs( numchars );
// Validate numchars parameter
if (numchars > stringparam.Length)
numchars = stringparam.Length;
return stringparam.Substring( 0, numchars );
}
/// <summary>
/// VB Right function
/// </summary>
/// <param name="stringparam"></param>
/// <param name="numchars"></param>
/// <returns>Right-most numchars characters</returns>
public static string Right( this string stringparam, int numchars )
{
// Handle possible Null or numeric stringparam being passed
stringparam += string.Empty;
// Handle possible negative numchars being passed
numchars = Math.Abs( numchars );
// Validate numchars parameter
if (numchars > stringparam.Length)
numchars = stringparam.Length;
return stringparam.Substring( stringparam.Length - numchars );
}
/// <summary>
/// VB Mid function - to end of string
/// </summary>
/// <param name="stringparam"></param>
/// <param name="startIndex">VB-Style startindex, 1st char startindex = 1</param>
/// <returns>Balance of string beginning at startindex character</returns>
public static string Mid( this string stringparam, int startindex )
{
// Handle possible Null or numeric stringparam being passed
stringparam += string.Empty;
// Handle possible negative startindex being passed
startindex = Math.Abs( startindex );
// Validate numchars parameter
if (startindex > stringparam.Length)
startindex = stringparam.Length;
// C# strings are zero-based, convert passed startindex
return stringparam.Substring( startindex - 1 );
}
/// <summary>
/// VB Mid function - for number of characters
/// </summary>
/// <param name="stringparam"></param>
/// <param name="startIndex">VB-Style startindex, 1st char startindex = 1</param>
/// <param name="numchars">number of characters to return</param>
/// <returns>Balance of string beginning at startindex character</returns>
public static string Mid( this string stringparam, int startindex, int numchars)
{
// Handle possible Null or numeric stringparam being passed
stringparam += string.Empty;
// Handle possible negative startindex being passed
startindex = Math.Abs( startindex );
// Handle possible negative numchars being passed
numchars = Math.Abs( numchars );
// Validate numchars parameter
if (startindex > stringparam.Length)
startindex = stringparam.Length;
// C# strings are zero-based, convert passed startindex
return stringparam.Substring( startindex - 1, numchars );
}
}
This extension method can be used as follows:
string myLongString = "Hello World!";
string myShortString = myLongString.Right(6); // "World!"
string myLeftString = myLongString.Left(5); // "Hello"
string myMidString1 = myLongString.Left(4); // "lo World"
string myMidString2 = myLongString.Left(2,3); // "ell"
