Calculating Fibonacci Numbers in C++ code

Question

My question is: I have a matrix. I need to calculate the corresponding Fibonacci number to each entry in that matrix, and return those values into another matrix. I keep getting a C2109 "Subscript requires array or pointer type", and I know where it's coming from, and I know what it means, but I don't know how to

fix it
make my code work.

Right now, it doesn't do anything. I'm not sure if I'm even returning any value from my Fibonacci function, or calling it correctly in my main function. I've modified it from what it originally was. Here's my new code:

const int     row1 = 3;
const int     col1row2 = 3;
const int     col2 = 3;

int fibonacci (int [][col2]);

void main()
{
     int   p[row1][col2],  f [row1][col2];
     int sum; 
     input (a,b); 

     cout<<"The Fibonacci Matrix is:   ";
     cout<<fibonacci(p);    
     for ( int  i = 0; i < row1; i++)
     {
          for ( int  j = 0; j < col2; j++)
              {
                    sum = f[i][j]; 
                    f[i][j] = fibonacci(p);           
              }
     }
     cout<<endl;
}


int fibonacci (int z[][col2])
{
     int   fib [100]  =  {0 , 1};
     int sum = 0;

     for ( int m = 2; m < 100; m++)
     {
           sum =  fib[m-1] + fib[m-2];
           fib[m] = sum;
     }
     return sum;
     cout<<endl;
}

Any help is appreciated!

It's refreshing to see somebody who actually has tried to solve the problem before asking - good job! — AndersK, Mar 02 '11 at 01:52
Thanks :) I was so worried posting a question on a site like this would result in getting made fun of :P — Sam, Mar 02 '11 at 02:02
@Sam we never, ever make fun of people. There's a "flag post" just for that and the moderators take it seriously. What often happens is that people are called out for not even showing that they made an attempt. You made an attempt and if you continue to do that before asking a question as you have done up here you're going to get an overwhelming outpouring of support from the community. — wheaties, Mar 02 '11 at 02:08
It's nice to have people that enjoy helping :) My teacher barely speaks english, and I find that with this program, a language barrier makes learning and understanding extremely difficult. As well, the students at school dislike helping and refuse to check over my code; sending me to this site. And I'm glad I did it :) Thanks everyone!! :) — Sam, Mar 02 '11 at 02:20
As a reminder, don't forget to mark an answer as correct by clicking the checkmark on the left of their text! — Marlon, Mar 02 '11 at 02:34

score 4 · Answer 1 · answered Mar 02 '11 at 01:54

I think the problem is that this line:

f [i][j] = fib [ p [i][j] ];

Is trying to call the fib function incorrectly. You have the right idea here, but to call a function in C++ you need to use regular parentheses rather than square brackets. I think this line should look like

f [i][j] = fib ( p [i][j] );

As a follow-up, your implementation of fib seems like it might be incorrect. In particular, you're taking in two parameters corresponding to the matrices, but you never use those values directly. Instead, you're constructing a new local array of all the Fibonacci numbers. You will probably want to have this function return the appropriate Fibonacci number it generates.

Hope this helps, and best of luck on your journey into C++!

score 2 · Answer 2 · answered Mar 02 '11 at 02:03

In addition to what templatetypedef said you are only supplying one argument to the fib function but declared it to take two arguments. Also the fib() doesn't return a value - its declared void.

fib( p [i][j] );

There is a semicolon missing also here

sum = fib[ m - 1]  +  fib[ m - 2]

Calculating Fibonacci Numbers in C++ code

2 Answers2