What method in the String class returns only the first N characters?

Question

I\'d like to write an extension method to the String class so that if the input string to is longer than the provided length N, only the first

Answer 1

if we are talking about validations also why we have not checked for null string entries. Any specific reasons?

I think below way help since IsNullOrEmpty is a system defined method and ternary operators have cyclomatic complexity = 1 while if() {} else {} has value 2.

    public static string Truncate(string input, int truncLength)
    {
        return (!String.IsNullOrEmpty(input) && input.Length >= truncLength)
                   ? input.Substring(0, truncLength)
                   : input;
    }

Answer 2

Simply:

public static String Truncate(String input,int maxLength)
{
   if(input.Length > maxLength)
      return input.Substring(0,maxLength);
   return input;
}

Answer 3

public static string TruncateLongString(this string str, int maxLength)
{
    return str.Length <= maxLength ? str : str.Remove(maxLength);
}

Answer 4

public static string TruncateLongString(this string str, int maxLength)
{
    if (string.IsNullOrEmpty(str))
        return str;
    return str.Substring(0, Math.Min(str.Length, maxLength));
}

Answer 5

I added this in my project just because where I'm using it is a high chance of it being used in loops, in a project hosted online hence I didn't want any crashes if I could manage it. The length fits a column I have. It's C#7

Just a one line:

 public static string SubStringN(this string Message, int Len = 499) => !String.IsNullOrEmpty(Message) ? (Message.Length >= Len ? Message.Substring(0, Len) : Message) : "";

Answer 6

Whenever I have to do string manipulations in C#, I miss the good old Left and Right functions from Visual Basic, which are much simpler to use than Substring.

So in most of my C# projects, I create extension methods for them:

public static class StringExtensions
{
    public static string Left(this string str, int length)
    {
        return str.Substring(0, Math.Min(length, str.Length));
    }

    public static string Right(this string str, int length)
    {
        return str.Substring(str.Length - Math.Min(length, str.Length));
    }
}

Note:
The Math.Min part is there because Substring throws an ArgumentOutOfRangeException when the input string's length is smaller than the requested length, as already mentioned in some comments under previous answers.

Usage:

string longString = "Long String";

// returns "Long";
string left1 = longString.Left(4);

// returns "Long String";
string left2 = longString.Left(100);