How can create N items of a specific element in c#?

Question

I am looking for a way to generate N pieces of question marks joined with comma.

string element="?";
string sep=",";
int n=4;
// code to run and create ?,?,?,?

• EDIT 1

I am looking in a simple way. Probably using 1-2 line of code. In c++ there are array fill() and joins.

• EDIT 2

I need this for Compact Framework

Answer 1

In C# I would do:

StringBuilder sb = new StringBuilder();
string element="?";
string sep=",";
int n=4;

for (int x = 0; x < n; x++)
{
    sb.Append(element);
    sb.Append(sep);
}

if (sb.Length > 0)
{
    // remove the final separator
    sb.Length -= sep.Length;
}

Console.WriteLine(sb.ToString());

Answer 2

Not concise but it'll do the trick..

StringBuilder sb = new StringBuilder();
sb.Append(element);
for(int i = 1; i < n; i++){
   sb.Append(sep);
   sb.Append(element);
}
string output = sb.toString();

Answer 3

StringBuilder sb = new StringBuilder();
for(int i=0;i<n;i++)
  sb.Append((i != n-1) ? "?," : "?");
string result = sb.ToString();

Answer 4

One line

String s = "".PadLeft(n-1, 'X').Replace("X", element+sep) + element;

Answer 5

string element = "?";
string sep = ",";
int n = 4;

string[] array = new string[n];

for (int i = 0; i < array.Length; i++) {
    array[i] = element;
}

string result = String.Join(sep, array);

Answer 6

        string output = "?";
        int n = 4;
        while (n > 1)
        { output += "," + "?"; n--; }

Answer 7

static string BuildSeparatedString(string element, string sep, int count)
{
  StringBuilder sb = new StringBuilder();

  for (int i = 1; i <= count; i++)
  {
    sb.Append(element);

    if (i != count)
      sb.Append(sep);
  }
  return sb.ToString();
}

It's not fancy but neither is it a cryptic one liner. Anyone reading or maintaining the code should very quickly understand it.

By some quick testing this also runs nearly twice as fast as the two most popular one liners.

Answer 8

var result = Enumerable.Repeat(element, n).DefaultIfEmpty("").Aggregate((s1, s2) => s1 + sep + s2);

Answer 9

static class Extensions
{
     public static string Times(this string s, int count)
     {
          StringBuilder sb = new StringBuilder(count * s.Length);
          for (int i = 0; i < count; i++)
          {
              sb.Append(s);
          }
          return sb.ToString();
     }
}

Usage:

Console.WriteLine("?,".Times(5).Trim(','));

Answer 10

Use the new Enumerable.Repeat method in conjunction with String.Join:

String.Join(sep, Enumerable.Repeat(element, n).ToArray());

Answer 11

Here is a one liner as well :)

 int n = 10;
 string element = "?";
 string sep = ",";

 string result = String.Join(sep, Enumerable.Range(0, n).Select(x => element).ToArray());

Answer 12

string result = String.Join(sep,Enumerable.Repeat(element, n).ToArray());

Answer 13

Here's another one-line expression to do what you want (with LINQ):

string.join(sep, (from x in Enumerable.Range(1, n) select element).ToArray())