Can someone explain this code

Question

can someone explain how this code run per line thanks and please no negative comments

CODE:

public static string Fib(int n)
{
if(n<2)
return "1";
int[ ] f = new int [n +1];
f[0] = 0;
f[1] = 0;
for (int i = 2; i <= n; i++)
{
f[ i ] = f[ i - 1] + f[ i - 2 ];
}
return string.Join(" ",f);
}

OUTPUT:

for example (int n = 5;)

0 1 1 2 3 5

Answer 1

It starts with f[0] and f[1] equal 0 and starts iterating over the list's items. The iteration builds an item by assigning it a value equal to the sum of the two previous ones. One exception - if n<2 it assigns 1.
Then what is returned is a string built by .joining all the list items together, separated by a blank space.

It's a standard code to produce the Fibonacci's sequence.

EDIT: by list I mean an array :)

Answer 2

the CODE contains some errors.

corrected variant:
public static string Fib(int n) {
if(n<2) return "0";
int[] f = new int[n];
f[0] = 0;
f[1] = 1;
for (int i=2; i<n; i++)
f[i]=f[i-1]+f[i-2];
return string.Join(" ",f);
}

for example,
Console.WriteLine(Fib(6));
output: 0 1 1 2 3 5

Fib function creates new array, then first two elements of array is initialized by 0 and 1, other elements is calculated. The result is returned as a string.