什么是Perl重复运算符的C＃等价物？

Question

In Perl

print "a" x 3;  # aaa

In C#

Console.WriteLine( ??? )

Answer 1

It depends what you need... there is new string('a',3) for example.

For working with strings; you could just loop... not very interesting, but it'll work.

With 3.5, you could use Enumerable.Repeat("a",3) , but this gives you a sequence of strings, not a compound string.

If you are going to use this a lot, you could use a bespoke C# 3.0 extension method:

    static void Main()
    {
        string foo = "foo";
        string bar = foo.Repeat(3);
    }
    // stuff this bit away in some class library somewhere...
    static string Repeat(this string value, int count)
    {
        if (count < 0) throw new ArgumentOutOfRangeException("count");
        if (string.IsNullOrEmpty(value)) return value; // GIGO            
        if (count == 0) return "";
        StringBuilder sb = new StringBuilder(value.Length * count);
        for (int i = 0; i < count; i++)
        {
            sb.Append(value);
        }
        return sb.ToString();
    }

Answer 2

如果您只需要重复单个字符（如您的示例中所示），那么这将起作用：

Console.WriteLine(new string('a', 3))

Answer 3

Well in all version of .NET to repeat a string you could always do this

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

Answer 4

If you need to do this with strings like Tom pointed out, then an extension method will do the job nicely.

static class StringHelpers
{
    public static string Repeat(this string Template, int Count)
    {
        string Combined = Template;
        while (Count > 1) {
            Combined += Template;
            Count--;
        }
        return Combined;
    }
}

class Program
{
    static void Main(string[] args)
    {
        string s = "abc";
        Console.WriteLine(s.Repeat(3));
        Console.ReadKey();
    }