Can I "multiply" a string (in C#)?

inspite_31765 0
Viewed 93634

Suppose I have a string, for example,

string snip =  "</li></ul>";

I want to basically write it multiple times, depending on some integer value. 

string snip =  "</li></ul>";
int multiplier = 2;

// TODO: magic code to do this 
// snip * multiplier = "</li></ul></li></ul>";

EDIT: I know I can easily write my own function to implement this, I was just wondering if there was some weird string operator that I didn't know about

extension-methods string c#
13 Answers

Note that if your "string" is only a single character, there is an overload of the string constructor to handle it:

int multipler = 10;
string TenAs = new string ('A', multipler);
user_127250

Unfortunately / fortunately, the string class is sealed so you can't inherit from it and overload the * operator. You can create an extension method though:

public static string Multiply(this string source, int multiplier)
{
   StringBuilder sb = new StringBuilder(multiplier * source.Length);
   for (int i = 0; i < multiplier; i++)
   {
       sb.Append(source);
   }

   return sb.ToString();
}

string s = "</li></ul>".Multiply(10);
user_89540

I'm with DrJokepu on this one, but if for some reason you did want to cheat using built-in functionality then you could do something like this:

string snip = "</li></ul>";
int multiplier = 2;

string result = string.Join(snip, new string[multiplier + 1]);

Or, if you're using .NET 4:

string result = string.Concat(Enumerable.Repeat(snip, multiplier));

Personally I wouldn't bother though - a custom extension method is much nicer.

Luke_558470

Just for the sake of completeness - here is another way of doing this:

public static string Repeat(this string s, int count)
{
    var _s = new System.Text.StringBuilder().Insert(0, s, count).ToString();
    return _s;
}

I think I pulled that one from Stack Overflow some time ago, so it is not my idea.

user_517100

You'd have to write a method - of course, with C# 3.0 it could be an extension method:

public static string Repeat(this string, int count) {
    /* StringBuilder etc */ }

then:

string bar = "abc";
string foo = bar.Repeat(2);
Marc_Gravell_233540 
string Multiply(string input, int times)
{
     StringBuilder sb = new StringBuilder(input.length * times);
     for (int i = 0; i < times; i++)
     {
          sb.Append(input);
     }
     return sb.ToString();
}
Chris_Ballance_15510

Since everyone is adding their own .NET4/Linq examples, I might as well add my own. (Basically, it DrJokepu's, reduced to a one-liner)

public static string Multiply(this string source, int multiplier) 
{ 
    return Enumerable.Range(1,multiplier)
             .Aggregate(new StringBuilder(multiplier*source.Length), 
                   (sb, n)=>sb.Append(source))
             .ToString();
}
user_127250

Okay, here's my take on the matter:

public static class ExtensionMethods {
  public static string Multiply(this string text, int count)
  {
    return new string(Enumerable.Repeat(text, count)
      .SelectMany(s => s.ToCharArray()).ToArray());
  }
}

I'm being a bit silly of course, but when I need to have tabulation in code-generating classes, Enumerable.Repeat does it for me. And yeah, the StringBuilder version is fine, too.

Dmitri_Nesteruk_94760
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