Best way to repeat a character in C#

What about this:

string tabs = new string('\t', n);

Where n is the number of times you want to repeat the string.

Or better:

static string Tabs(int n)
{
    return new string('\t', n);
}

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string.Concat(Enumerable.Repeat("ab", 2));

Returns

"abab"

And

string.Concat(Enumerable.Repeat("a", 2));

Returns

"aa"

from...

Is there a built-in function to repeat string or char in .net?

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In all versions of .NET, you can repeat a string thus:

public static string Repeat(string value, int count)
{
    return new StringBuilder(value.Length * count).Insert(0, value, count).ToString();
}

To repeat a character, new String('\t', count) is your best bet. See the answer by @CMS.

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The best version is certainly to use the builtin way:

string Tabs(int len) { return new string('\t', len); }

Of the other solutions, prefer the easiest; only if this is proving too slow, strive for a more efficient solution.

If you use a StringBuilder and know its resulting length in advance, then also use an appropriate constructor, this is much more efficient because it means that only one time-consuming allocation takes place, and no unnecessary copying of data. Nonsense: of course the above code is more efficient.

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Extension methods:

public static string Repeat(this string s, int n)
{
    return new String(Enumerable.Range(0, n).SelectMany(x => s).ToArray());
}

public static string Repeat(this char c, int n)
{
    return new String(c, n);
}

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What about using extension method?

public static class StringExtensions
{
   public static string Repeat(this char chatToRepeat, int repeat) {

       return new string(chatToRepeat,repeat);
   }
   public  static string Repeat(this string stringToRepeat,int repeat)
   {
       var builder = new StringBuilder(repeat*stringToRepeat.Length);
       for (int i = 0; i < repeat; i++) {
           builder.Append(stringToRepeat);
       }
       return builder.ToString();
   }
}

You could then write :

Debug.WriteLine('-'.Repeat(100)); // For Chars  
Debug.WriteLine("Hello".Repeat(100)); // For Strings

Note that a performance test of using the stringbuilder version for simple characters instead of strings gives you a major preformance penality : on my computer the difference in mesured performance is 1:20 between: Debug.WriteLine('-'.Repeat(1000000)) //char version and Debug.WriteLine("-".Repeat(1000000)) //string version

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How about this:

//Repeats a character specified number of times
public static string Repeat(char character,int numberOfIterations)
{
    return "".PadLeft(numberOfIterations, character);
}

//Call the Repeat method
Console.WriteLine(Repeat('\t',40));

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I know that this question is five years old already but there is a simple way to repeat a string that even works in .Net 2.0.

To repeat a string:

string repeated = new String('+', 3).Replace("+", "Hello, ");

Returns

"Hello, Hello, Hello, "

To repeat a string as an array:

// Two line version.
string repeated = new String('+', 3).Replace("+", "Hello,");
string[] repeatedArray = repeated.Split(',');

// One line version.
string[] repeatedArray = new String('+', 3).Replace("+", "Hello,").Split(',');

Returns

{"Hello", "Hello", "Hello", ""}

Keep it simple.

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Let's say you want to repeat '\t' n number of times, you can use;

String.Empty.PadRight(n,'\t')

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Your first example which uses Enumerable.Repeat:

private string Tabs(uint numTabs)
{
    IEnumerable<string> tabs = Enumerable.Repeat(
                                 "\t", (int) numTabs);
    return (numTabs > 0) ? 
            tabs.Aggregate((sum, next) => sum + next) : ""; 
} 

can be rewritten more compactly with String.Concat:

private string Tabs(uint numTabs)
{       
    return String.Concat(Enumerable.Repeat("\t", (int) numTabs));
}

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Using String.Concat and Enumerable.Repeat which will be less expensive than using String.Join

public static Repeat(this String pattern, int count)
{
    return String.Concat(Enumerable.Repeat(pattern, count));
}

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var str = new string(Enumerable.Repeat('\t', numTabs).ToArray());

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The answer really depends on the complexity you want. For example, I want to outline all my indents with a vertical bar, so my indent string is determined as follows:

return new string(Enumerable.Range(0, indentSize*indent).Select(
  n => n%4 == 0 ? '|' : ' ').ToArray());

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And yet another method

new System.Text.StringBuilder().Append('\t', 100).ToString()

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For me is fine:

public static class Utils
{
    public static string LeftZerosFormatter(int zeros, int val)
    {
        string valstr = val.ToString();

        valstr = new string('0', zeros) + valstr;

        return valstr.Substring(valstr.Length - zeros, zeros);
    }
}

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You can create an extension method

static class MyExtensions
{
    internal static string Repeat(this char c, int n)
    {
        return new string(c, n);
    }
}

Then you can use it like this

Console.WriteLine('\t'.Repeat(10));

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Without a doubt the accepted answer is the best and fastest way to repeat a single character.

Binoj Anthony's answer is a simple and quite efficient way to repeat a string.

However, if you don't mind a little more code, you can use my array fill technique to efficiently create these strings even faster. In my comparison tests, the code below executed in about 35% of the time of the StringBuilder.Insert code.

public static string Repeat(this string value, int count)
{
    var values = new char[count * value.Length];
    values.Fill(value.ToCharArray());
    return new string(values);
}

public static void Fill<T>(this T[] destinationArray, params T[] value)
{
    if (destinationArray == null)
    {
        throw new ArgumentNullException("destinationArray");
    }

    if (value.Length > destinationArray.Length)
    {
        throw new ArgumentException("Length of value array must not be more than length of destination");
    }

    // set the initial array value
    Array.Copy(value, destinationArray, value.Length);

    int copyLength, nextCopyLength;

    for (copyLength = value.Length; (nextCopyLength = copyLength << 1) < destinationArray.Length; copyLength = nextCopyLength)
    {
        Array.Copy(destinationArray, 0, destinationArray, copyLength, copyLength);
    }

    Array.Copy(destinationArray, 0, destinationArray, copyLength, destinationArray.Length - copyLength);
}

For more about this array fill technique, see Fastest way to fill an array with a single value

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Try this:

Add Microsoft.VisualBasic reference Use: String result = Microsoft.VisualBasic.Strings.StrDup(5,"hi"); Let me know if it works for you.

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Fill the screen with 6,435 z's $str = [System.Linq.Enumerable]::Repeat([string]::new("z", 143), 45)

$str

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Albeit very similar to a previous suggestion, I like to keep it simple and apply the following:

string MyFancyString = "*";
int strLength = 50;
System.Console.WriteLine(MyFancyString.PadRight(strLength, "*");

Standard .Net really,

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