In this tutorial, we’ll be doing a C# Program to print Fibonacci Series.
// C# Program to print out Fibonacci Series. using System; public class Fibonacci { static void Main(string[] args) { int x=0,y=1,z,i,number; Console.Write("Upto how many numbers? "); number = int.Parse(Console.ReadLine()); Console.Write(x+" "+y+" "); //printing 0 and 1 for(i=2;i<number;++i) //loop starts from 2 because 0 and 1 are already printed { z=x+y; Console.Write(z+" "); x=y; y=z; } } }
Output:
Here, the output of fibonacci series in C# programming.
Upto how many numbers? 10 0 1 1 2 3 5 8 13 21 34

Explaination:
We’ve already explained about the basic structure and parameter of C# program so, let’s go through the main program.
int x=0, y=1, z, i, number;
Here, x, y, z, i & number are interger variables. The initial value of x & y is set to 0 and 1 respectively. Variable i is used as loop counter. Similary, number is used for storing the number entered by the user.
Console.Write("Upto how many numbers? ");
This line simply displays a Message written inside the quotation box. Here, we write a message for the user to enter a number of steps to print out Fibonacci Series.
number = int.Parse(Console.ReadLine());
This line just accepts the number (intger value) entered by the user and store it in the inter variable number.
Console.Write(x+" "+y+" ");
This line simply prints 0 and 1.
for(i=2;i<number;++i) { z=x+y; Console.Write(z+" "); x=y; y=z; }
Basically, this block of codes simply runs the loop (number-2) times. Inside each loop, it prints the sum(z) of the last two digits (x and y) & updates value of x by value of y & value of y by value of z.
In this way, the C# program to print out Fibonacci Series.
Also Read: C# Hello World
C# Program to check whether the number is prime or not.
C Sharp for Beginners