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Nov 3rd, 2004

I need help writing a program using Fibonacci sequence

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The program needs to ask for n and then output the first n terms of the Fibonacci sequence.

exp.
n = 6
1, 1, 2, 3, 5, 8
1+1 =2
2+1=3
3+2=5
5+3=8

My origional program used a nested for loop.
I am not sure if that is right to use in this type a situation.
I would like suggestions to make it work.

#include <iostream>

using namespace std;
int main ()
{
int fOne = 1;
int fTwo = 1;
int fThree = 2;
long fN;
long fNN;

cout << "How many n terms do you want in the sequence: ";
cin >> fN;

for ( fN = 1 ; fN >= 3 ; fN++ )
{
for (fNN = 1; fNN >= fN; fNN++)
fNN = (fN - 1) + (fN - 2);
cout << fN;
}
}

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gpleonar

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Nov 3rd, 2004

Re: I need help writing a program using Fibonacci sequence

You have some mistakes in this code:

Quote ...

cin >> fN;

for ( fN = 1 ; fN >= 3 ; fN++ )

As you introduce fN from the standard input, why are you initializing it in the for loop? More, if you are initializing fN = 1, then the condition in for loop fN >= 3 is never accomplished.

Then, for the Fibonacci series, as I know, every term of the series, starting with the third term, is the sum of the 2 preceding terms. In a vector, this should be a[n] = a[n-1] + a[n-2], right?
Or, in the for loop

C++ Syntax (Toggle Plain Text)
for (fNN = 1; fNN >= fN; fNN++)
    fNN = (fN - 1) + (fN - 2);
cout << fN;
for (fNN = 1; fNN >= fN; fNN++)
    fNN = (fN - 1) + (fN - 2);
cout << fN;

you are adding the same term, subtracting from it first 1, then 2..this is not exactly what you want...

frrossk

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Nov 3rd, 2004

Re: I need help writing a program using Fibonacci sequence

Here you have some sample code:

C++ Syntax (Toggle Plain Text)
#include <iostream> 
 
using namespace std;
int main ()
{
int a[128];
int fN;
int i;
 
a[0]=1;
a[1]=1;
 
cout << "How many n terms do you want in the sequence: ";
cin >> i;
 
for ( fN = 2 ; fN <= i ; fN++ )
{
a[fN]=a[fN-1]+a[fN-2];
cout << a[fN] <<"\n";
}
}
#include <iostream> 

using namespace std;
int main ()
{
int a[128];
int fN;
int i;

a[0]=1;
a[1]=1;

cout << "How many n terms do you want in the sequence: ";
cin >> i;

for ( fN = 2 ; fN <= i ; fN++ )
{
a[fN]=a[fN-1]+a[fN-2];
cout << a[fN] <<"\n";
}
}

It has some limitations (you can't enter a value >128, for example), but I hope you get the idea.

frrossk

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Apr 29th, 2007

Re: I need help writing a program using Fibonacci sequence

Okay, when I ran this program, I saw one error:
1. I did not see the first two ones in the Fibonacci sequence.

Also, can you tell me that the a and the i means in this program??

naya22

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Apr 29th, 2007

Re: I need help writing a program using Fibonacci sequence

>1. I did not see the first two ones in the Fibonacci sequence.
Probably because those values weren't printed. They're in the generated sequence though. frrossk's program kind of sucks anyway.

>Also, can you tell me that the a and the i means in this program??
a is an array that holds each number in the sequence and i is the expected length of the sequence.

Narue

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Apr 29th, 2007

Re: I need help writing a program using Fibonacci sequence

> Nov 3rd 2004
> 2 Minutes Ago
Lets see, 2 and a half years.
Now, what was your question again?

Salem

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Posting Sage

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Apr 29th, 2007

Re: I need help writing a program using Fibonacci sequence

I don't see a problem resurrecting the thread in this case.

Narue

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Mar 3rd, 2010

-2

Re: I need help writing a program using Fibonacci sequence

hey i have this code..... n it works

# include <iostream.h>
void main ()
{
int x=0, y=1, b, n=0,ter;

cout<<"Enter The number of terms";
cin>>ter;
cout<<x<<" "<<y<<" ";

while (n<ter-1)
{
b=x+y;
cout<<b<<" ";
x=y;
y=b;

n++;
}

}

DrAgon PrinceSS

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Mar 3rd, 2010

Re: I need help writing a program using Fibonacci sequence

you do realize this thread is almost 6-years old... the OP has probably completely forgotten about it by now.

Fbody

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Posting Maven

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Mar 3rd, 2010

Re: I need help writing a program using Fibonacci sequence

LOL. wht can i say .. i just started c++ and made this prog today.!

DrAgon PrinceSS

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