C# – Display Triangle Patterns

using System;

namespace ConsoleApp20
{
class Program
{
static void Main(string[] args)
{
const int ROWS = 5;
const int COLUMNS = 5;

Console.WriteLine(" Left to Right");
for (int i1 = 1, i2 = 1; i1 < COLUMNS * 2; i1++)
{
for (int j = 1; j <= i2; j++)
{
Console.Write(" *");
}

if (i1 < 5)
i2++;
else
i2--;
Console.WriteLine();
}
Console.WriteLine();

Console.WriteLine(" Right to Left");
for (int i1 = 1, i2 = COLUMNS - 1, i3 = 1; i1 < COLUMNS * 2; i1++)
{
for (int j = 1; j <= i2; j++)
Console.Write(" ");

for (int j = 1; j <= i3; j++)
Console.Write(" *");

if (i1 < COLUMNS)
{
i3++;
i2--;
}
else
{
i3--;
i2++;
}
Console.WriteLine();
}
Console.WriteLine();

Console.WriteLine(" Bottom to Top");
for (int i1 = 1; i1 <= ROWS; i1++)
{
for (int j = i1; j < ROWS; j++)
Console.Write("  ");

for (int j = 1; j <= (2 * i1 - 1); j++)
Console.Write(" *");
Console.WriteLine();
}

Console.WriteLine("\n Top to Bottom");
for (int i1 = 1; i1 <= ROWS; i1++)
{
for (int j = 1; j < i1; j++)
Console.Write("  ");

for (int j = 1; j <= (ROWS * 2 - (2 * i1 - 1)); j++)
Console.Write(" *");

Console.WriteLine();
}
Console.WriteLine();
Console.ReadKey();
}
}
}

Output