For loop is control statement. It is a keyword used for repetitive execution of statement. For loop executes a block of statements repeatedly until the specified condition returns true/false value. It is one of the easiest loop and mostly  used.

The syntax of for loop is

for(variable declaration/initialization; condition; steps(increment/decrement))

{

//statements

}

Flowchart of  for loop

1. Variable declaration= integer type. Example: int i; int j; Initialization = the beginning value of the variable. Example: i=0; i=20 etc.
2. Condition:  The condition in loop is Boolean expression which returns either True or False. Example:  i<10; i<=20; I > 5; I >=10 ;
3. Increment / decrement : It defines increment or decrement part: It executes only when the condition is satisfied.

Example: 

i++ , i-- ,i=i+2, i=i-2

Example of for loop

for ( int i=0; i<=10;i++) 

for (i=2;i<=20; i=i+2)

for (i=10; i>=0 ; i--)

Question: How to display pyramid using for loop in C# ?

Solution:

using System;
namespace Star_Pyramid
{
    class Program
    {
        static void Main(string[] args)
        {
            int i, j, k, n;
            Console.WriteLine("how many number of pyramid do you want");
            n = int.Parse(Console.ReadLine());
            for (i = 1; i <= n; i++)
            {
                for ( j = 1; j <=(n - i) / 2; j++)
                {
                    Console.Write("   ");
                }
                for ( k = 1; k <= i-1; k++)
                {
                    Console.Write(" * ");
                    Console.Write(" ");
                }
                Console.WriteLine();
            }
            Console.ReadKey();
        }
    }
}

Output of  above program is shown below