Google introduced Carbon programming language with a modern language syntax to become a successor to C++.

One of the challenges many beginner developers are facing is to run basic examples since the language is in a very early stage without even having a compiler. So here is a working example to print fibonacci series using Carbon language.

## How to print fibonacci series in carbon lang

To recollect Fibonacci series, here the following sequence that we want to print.

`0, 1, 1, 2, 3, 5, 8, 13, 21 ....`

Currently, there is no support `<`

symbol yet in Carbon language. Also `for`

loop is not yet supported in carbon language. So we will use different approach.

To print fibonacci series in carbon, we will use combination of recursion + iteration to print fibonacci sequence. Here are 2 steps we follow.

- Print nth fibonacci number in Carbon programming language
- Print fibonacci sequence using While loop in carbonlang

Let's dive in

## Step 1: Print nth fibonacci number in Carbon language

We use a recursive code to calculate nth fibonacci number using the follow recursive formula.

```
fib(n) = fib(n-1) + fib(n-2);
if n <= 1 we can just print n.
```

Let's write code in carbon language.

```
fn Square(x: i32) -> i32 {
return x * x;
}
fn fib(n: i32) -> i32 {
if(n == 0) {
return 0;
}
if(n == 1) {
return 1;
}
return fib(n - 1) + fib(n - 2);
}
```

## Step 2: Print fibonacci sequence using While loop in carbonlang

The next step is the call fib(n) for n times. This can be achieved using while loop.
Observe fib(i) inside `Print`

method.

```
fn fibSeries(count: i32) {
var i: i32 = count;
while(not (i == 0)) {
Print("{0}", fib(i));
i = i - 1;
}
}
```

## Print fibonacci sequence in carbonlang

Connecting two pieces together, we can have

```
package sample api;
fn Square(x: i32) -> i32 {
return x * x;
}
fn fib(n: i32) -> i32 {
if(n == 0) {
return 0;
}
if(n == 1) {
return 1;
}
return fib(n - 1) + fib(n - 2);
}
fn fibonacciSeries(count: i32) {
var i: i32 = count;
while(not (i == 0)) {
Print("{0}", fib(i));
i = i - 1;
}
}
fn Main() -> i32 {
var n: i32 = 6;
Print("Input n: {0}", n);
Print("nth fibonacci number result: {0}", fib(n));
Print("-----------", n);
Print("Fibonacci series for n = {0}", n);
fibonacciSeries(10);
return 0;
}
```

The output for this would be

```
Input n: 6
nth fibonacci number result: 8
-----------
Fibonacci series for n = 6
55
34
21
13
8
5
3
2
1
1
```

You can try this by yourself using carbon language compiler explorer online: Compiler explorer

Additional Reading in Carbon language:

Carbon language memory safety for secure memory management: Carbon language memory management

This is a part of carbon language series for beginners. Will share carbon language tips and working examples regularly. You can view full carbon language tutorial video here.

### Carbon language short course

If you find other better ways to print fibonacci series in carbon, share your thoughts in the comments.

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