Pad Left & Pad Right (Pad Center) String

Question

String has both PadLeft and PadRight . I am in need of padding both left and right (center justification). Is there a standardized way of doing this, or better yet, a built in way of achieving the same goal?

Answer 1

Not that I know of. You can create an extension method if you see yourself using it a lot. Assuming you want your string to end up in the center, use something like the following

public string PadBoth(string source, int length)
{
    int spaces = length - source.Length;
    int padLeft = spaces/2 + source.Length;
    return source.PadLeft(padLeft).PadRight(length);

}

To make this an extension method, do it like so:

namespace System
{
    public static class StringExtensions
    {
        public static string PadBoth(this string str, int length)
        {
            int spaces = length - str.Length;
            int padLeft = spaces / 2 + str.Length;
            return str.PadLeft(padLeft).PadRight(length);
        }
    }
}

As an aside, I just include my extensions in the system namespace - it's up to you what you do.

Answer 2

Here is a custom implementation, not requiring rebuilding of strings.

Also it works correctly with odd numbers

    static string PadCenter(string text, int newWidth)
    {
        const char filler = ' ';
        int length = text.Length;
        int charactersToPad = newWidth - length;
        if (charactersToPad < 0) throw new ArgumentException("New width must be greater than string length.", "newWidth");
        int padLeft = charactersToPad/2 + charactersToPad%2;
        //add a space to the left if the string is an odd number
        int padRight = charactersToPad/2;

        StringBuilder resultBuilder = new StringBuilder(newWidth);
        for (int i = 0; i < padLeft; i++) resultBuilder.Insert(i, filler); 
        for (int i = 0; i < length; i++) resultBuilder.Insert(i + padLeft, text[i]); 
        for (int i = newWidth - padRight; i < newWidth; i++) resultBuilder.Insert(i, filler);
        return resultBuilder.ToString();
    }

Answer 3

Here's a slightly improved version of @david-colwell's extension method that also optionally takes a padding character:

namespace System
{
    public static class StringExtensions
    {
        public static string PadSides(this string str, int totalWidth, char paddingChar = ' ')
        {
            int padding = totalWidth - str.Length;
            int padLeft = padding / 2 + str.Length;
            return str.PadLeft(padLeft, paddingChar).PadRight(totalWidth, paddingChar);
        }
    }
}

Answer 4

You could do it yourself with this:

    string test = "Wibble";
    int padTo = 12;
    int padSize = (padTo - test.Length) / 2;
    if (padSize > 0) {
        test = test.Trim().PadLeft(test.Length + padSize).PadRight(test.Length + 2 * padSize);
    }

Just adjust this to deal with odd padding lengths as required and make it an extension method if that makes your life easier.

Answer 5

Here a bit of an improvement I think.

namespace System
{
    public static class StringExtensions
    {
        public static string PadCenter(this string str, int totalLength, char padChar = '\u00A0')
        {
            int padAmount = totalLength - str.Length;

            if (padAmount <= 1)
            {
                if (padAmount == 1)
                {
                    return str.PadRight(totalLength);
                }
                return str;
            }

            int padLeft = padAmount/2 + str.Length;

            return str.PadLeft(padLeft).PadRight(totalLength);
        }
    }
}

Answer 6

After reading this, I would like to provide one other function that is helpful (in printing).

This is not to be taken as an answer to this question, but builds on it.

based on @orad's answer.

public static string PadSplit(string str1, string str2, int totalWidth, char paddingChar = ' ')
{
        string output;
        int paddingWidth = totalWidth - (str1.Length + str2.Length);
        output = string.Format("{0}{1}{2}", str1, string.Empty.PadCenter(paddingWidth, paddingChar), str2);
        return output;
}

PadSplit("David", "Wins", 16) => "David       Wins"

Answer 7

  /* Output looks like this
       *****Luke***** 
       *****Leia*****
       *****Han******
       **Chewbecca***  */

  string result = "";
   string names = "Luke,Leia,Han,Chewbecca";
   string[] charA = names.Split(',');

        for (int i = 0; i < charA.Length; i++)
        {
            int padLeft = (14 - charA[i].Length) / 2;
            string temp = charA[i].PadLeft(charA[i].Length + padLeft, '*');
            result += temp.PadRight(14, '*') + "\n";
        }
        Console.WriteLine(result);

Answer 8

you can also create your extension like this:

public static string PadBoth(this string s, int padValue)
{
    return s.PadLeft(padValue).PadRight(padValue);
}

and use PadBoth method on string.