Display the pattern like diamond by using c# for loop, C#

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
           
            int i, j, r;

Console.Write("\n\n");
            Console.Write("Display the pattern like diamond:\n");
            Console.Write("-----------------------------------");
            Console.Write("\n\n");

r = 3;
            for (i = 1; i <= r; i++)
            {
                for (j = 1; j <= r - i; j++)
                    Console.Write(" ");
                for (j = 1; j <= 2 * i - 1; j++)
                    Console.Write(i);
                Console.Write("\n");
            }

for (i = r - 1; i >= 1; i--)
            {
                for (j = 1; j <= r - i; j++)
                    Console.Write(" ");
                for (j = 1; j <= 2 * i - 1; j++)
                    Console.Write(i);
                Console.Write("\n");
            }

}
    }
}

Show compiler warnings [ + ] Show input
Compilation time: 0,14 sec, absolute running time: 0,09 sec, cpu time: 0,08 sec, average memory usage: 12 Mb, average nr of threads: 2