Hi there guys.

Literally I have been asked this question;

"The Fibonacci sequence is 0, 1, 1, 2, 3, 5, 8, 13, … ; the first two terms are 0 and 1, and each term thereafter is the sum of the two preceding terms – i.e., Fib[n] = Fib[n – 1] + Fib[n – 2]. Using this information, write a C++ program that calculates the nth number in a Fibonacci sequence, where the user enters n in the program interactively. For example, if n = 6, the program should display the value 5."

I have created the program, but I want to give the User an option to either go back to the start of the program, or to quit it. i.e. I don't want them to have to continually click 'Run'. I know this is something to do with the 'Do While' Loop, but I am a bit of a novice and not really sure how to go about it/code it.

Any thoughts on my question and/or examples/walkthroughs would be much appreciated, just trying to get my head round it. Any suggestions to improve my code so far is also welcome. Thank you! :)

Here is my code so far.

#include <iostream>
#include <cmath>

using namespace std;

int main() {

    int N;

    cout<<"This program is designed to give the user any value of the Fibonacci Sequence that they desire, provided the number is a positive integer.";//Tell user what the program does

    cout<<"\n\nThe formula of the Fibonacci Sequence is;   Fib[N] = Fib[N – 1] + Fib[N – 2]\n\n"; //Declare the Formula for the User

    cout<<"Enter a value for N, then press Enter:"; //Declare Value that the User wants to see

    cin>>N;//Enter the Number

    if (N>1) {
        cout<<"\nFor your value of N, \nFib[N]= "<<((pow(((1+(pow(5, 0.5)))), N))-(pow(((1-(pow(5, 0.5)))), N)))*(pow((pow(2.0, N)*(pow(5, 0.5))), -1));//Mathematic formula for Fibonacci Sequence
    }

    if (N<0) {
        cout<<"\n\nThe value N must be a POSITIVE integer, i.e. N > 0"; //Confirm that N must be a positive integer. Loop.
    }
    if (N>100) {
        cout<<"\n\nThe value for N must be less than 100, i.e. N < 100. N must be between 0 - 100.";//Confirm that N must be less than 100. Loop.
    }
    if (N==0) {
        cout<<"\n\nFor your value of N, \nFib[0] = 0"; //Value will remain constant throughout, cannot be caculated through formula. Loop.
    }
    if (N==1) {
        cout<<"\n\nFor your value of N. \nFib[1]=1";//Value will remain constant throughout, cannot be caculated through formula. Loop.
    }


    return 0;
}

PS Sorry for it all being in Green, just the way it came out. Obviously not displayed like that in the actually program.

Okay, it didn't actually all display in green, never mind that comment!

Also changed it to,

if (N>1 and N<100) {
        cout<<"\nFor your value of N, \nFib[N]= "<<((pow(((1+(pow(5, 0.5)))), N))-(pow(((1-(pow(5, 0.5)))), N)))*(pow((pow(2.0, N)*(pow(5, 0.5))), -1));//Mathematic formula for Fibonacci Sequence

to stop values of over 100 being entered. Cheers

You need to wrap the body of your code (lines 10-33) inside a loop. When the result is displayed, ask the user if they want to find another, get at yes/no type response, check it.

You would want to wrap lines 10-33 in a do-while loop.

int continue = 0;
do
{
    //lines 10-33
    cout << "Do you want to go agian? << endl
    cout << "Enter 1 for yes 0 for no: ";
    cin >> continue;
} while (continue != 0) // doing this to allow all non 0 numbers to continue

This should get you started. You probably want to have some input verification so that you can have a more specific while condition.

Thanks very much I will give it a try. However I come up witht he problem that one of the conditions specified for this assignment is "Some of you have inquired if you can use a formula (available on the web) to calculate the Fibonacci series. The answer is: NO."

While I have no actually any of my code from online (I did it in maths last year), I can't see my argument holding.

So now I have a new question, can anyone possible give hints/tips/steps to calculate the answer?

I have a basic understanding, its just I don't know how to write the code to calculate the answer with the formula Fn = Fn-1 +Fn+2.

Badly worded question, but hard to say. Any help with this question/writing it in code would be much appriciated. Thanks again

Also, Nathan Oliver, I tried your method but the int continue = 0 comes up with the error 'unqualified ID'. What can I do to fix this? Here is code now.

#include <iostream>
#include <cmath>

using namespace std;

int main() {

      int N;
      int continue = 0

    do {
        cout<<"This program is designed to give the user any value of the Fibonacci Sequence that they desire, provided the number is a positive integer.";//Tell user what the program does

        cout<<"\n\nThe formula of the Fibonacci Sequence is;   Fib[N] = Fib[N – 1] + Fib[N – 2]\n\n"; //Declare the Formula for the User

        cout<<"Enter a value for N, then press Enter:"; //Declare Value that the User wants to see

        cin>>N;//Enter the Number

        if (N>1 and N<100) {
            cout<<"\nFor your value of N, \nFib[N]= "<<((pow(((1+(pow(5, 0.5)))), N))-(pow(((1-(pow(5, 0.5)))), N)))*(pow((pow(2.0, N)*(pow(5, 0.5))), -1));//Mathematic formula for Fibonacci Sequence
        }

        if (N<0) {
            cout<<"\n\nThe value N must be a POSITIVE integer, i.e. N > 0"; //Confirm that N must be a positive integer. Loop.
        }
        if (N>100) {
            cout<<"\n\nThe value for N must be less than 100, i.e. N < 100. N must be between 0 - 100.";//Confirm that N must be less than 100. Loop.
        }
        if (N==0) {
            cout<<"\n\nFor your value of N, \nFib[0] = 0"; //Value will remain constant throughout, cannot be caculated through formula. Loop.
        }
        if (N==1) {
            cout<<"\n\nFor your value of N. \nFib[1]=1";//Value will remain constant throughout, cannot be caculated through formula. Loop.
        }

        {
            cout<<"Do you want to enter another number?";
            cout<<"Enter 1 to continue and 0 to exit";
            cin>>continue;

    } while (continue ! = 0);

    return 0;
}


}

you need a ; at the end of line 9. Also change continue ! = 0 on line 42 to continue != 0. As far as an algorithim for the fib series there are plenty of threads on this site that you can read to see how you would do it.

Thanks again Nathan. I ended up using a char function which worked. And yeah, I have looked, but the majority I have seen have been people asking if there code is perfect etc....rather not copy was just looking for few started points/steps which I could work on myself then refer back to other peoples questions if needed.

continue is a keyword in C++. Use a different name.

Thanks deceptikon. I cant believe I used a keyword for a varibale name. Shame on me :(

Often, the fibonacci sequence is computed using a recursive function as shown in your comments (except for 0 and 1), and fib(6) == 8, not 5. I think the teacher wants you to learn how to write a recursive function instead of plugging in a formula that you looked up on the web. The function signature would be something like this: unsigned long fib(unsigned long n);

rubberman, thanks for that. Not sure what you mean by "fib(6) == 8, not 5"?

So far I have this code (too add to code above);

long long Fibonacci(int N);

int main()
{
    cout<<"Input Fibonacci Index number: ";
    int Index = 0;
    cin>> Index;
    cout<<"Answer"<<Fibonacci(N)<<endl;
    return 0;

}
long long Fibonacci(int input)
{
    if (N < 2)
        return N;
    else
    {
        return Fibonacci(N - 1) + Fibonacci(N - 2);
    }
}

However I am not sure about the

 cout<<"Input Fibonacci Index number: ";
    int Index = 0;
    cin>> Index;
    cout<<"Answer"<<Fibonacci(N)<<endl;
    return 0;

As it returns an error of not being able to identify N. This part of the code I got from looking at his notes. ANy help appriciated, just shooting in the dark here really, trial and error