Trim last character from a string

String withoutLast = yourString.Substring(0,(yourString.Length - 1));

"Hello! world!".TrimEnd('!');

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EDIT:

What I've noticed in this type of questions that quite everyone suggest to remove the last char of given string. But this does not fulfill the definition of Trim method.

Trim - Removes all occurrences of white space characters from the beginning and end of this instance.

MSDN-Trim

Under this definition removing only last character from string is bad solution.

So if we want to "Trim last character from string" we should do something like this

Example as extension method:

public static class MyExtensions
{
  public static string TrimLastCharacter(this String str)
  {
     if(String.IsNullOrEmpty(str)){
        return str;
     } else {
        return str.TrimEnd(str[str.Length - 1]);
     }
  }
}

Note if you want to remove all characters of the same value i.e(!!!!)the method above removes all existences of '!' from the end of the string, but if you want to remove only the last character you should use this :

else { return str.Remove(str.Length - 1); }

if (yourString.Length > 1)
    withoutLast = yourString.Substring(0, yourString.Length - 1);

or

if (yourString.Length > 1)
    withoutLast = yourString.TrimEnd().Substring(0, yourString.Length - 1);

...in case you want to remove a non-whitespace character from the end.