.NET equivalent of the old vb left(string, length) function

Question

As a non-.NET programmer I\'m looking for the .NET equivalent of the old Visual Basic function left(string, length). It was lazy in that it worked for any lengt

Answer 1

Use:

using System;

public static class DataTypeExtensions
{
    #region Methods

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

    public static string Right(this string str, int length)
    {
        str = (str ?? string.Empty);
        return (str.Length >= length)
            ? str.Substring(str.Length - length, length)
            : str;
    }

    #endregion
}

It shouldn't error, returns nulls as empty string, and returns trimmed or base values. Use it like "testx".Left(4) or str.Right(12);

Answer 2

I like doing something like this:

string s = "hello how are you";
s = s.PadRight(30).Substring(0,30).Trim(); //"hello how are you"
s = s.PadRight(3).Substring(0,3).Trim(); //"hel"

Though, if you want trailing or beginning spaces then you are out of luck.

I really like the use of Math.Min, it seems to be a better solution.

Answer 3

If you want to avoid using an extension method and prevent an under-length error, try this

string partial_string = text.Substring(0, Math.Min(15, text.Length)) 
// example of 15 character max

Answer 4

Don't forget the null case:

public static string Left(this string str, int count)
{
    if (string.IsNullOrEmpty(str) || count < 1)
        return string.Empty;
    else
        return str.Substring(0,Math.Min(count, str.Length));
}

Answer 5

Just in a very special case:

If you are doing this left and you will check the data with some partial string, for example:

if(Strings.Left(str, 1)=="*") ...;

Then you can also use C# instance methods, such as StartsWith and EndsWith to perform these tasks.

if(str.StartsWith("*"))...;

Answer 6

You could make your own:

private string left(string inString, int inInt)
{
    if (inInt > inString.Length)
        inInt = inString.Length;
    return inString.Substring(0, inInt);
}

Mine is in C#, and you will have to change it for Visual Basic.