C# example to print alphabet triangle.

 using System;  
 using System.Collections.Generic;  
 using System.Linq;  
 using System.Text;  
 using System.Threading.Tasks;  
 namespace ConsoleApp2  
 {  
   class Program  
   {  
     public static void Main(string[] args)  
     {  
       char ch = 'A';  
       int i, j, k, m;  
       for (i = 1; i <= 5; i++)  
       {  
         for (j = 5; j >= i; j--)  
           Console.Write(" ");  
         for (k = 1; k <= i; k++)  
           Console.Write(ch++);  
         ch--;  
         for (m = 1; m < i; m++)  
           Console.Write(--ch);  
         Console.Write("\n");  
         ch = 'A';  
       }  
       Console.ReadLine();  
     }  
   }  
 }