Fibonacci sequence

[metulburr]

I have been trying to do this Fibonacci sequence with the default args for awhile. I keep coming up with incorrect results. The total should be 4613732. and as it goes up, the 4 should be a five, and the 7 should be an eight, etc.

1
2
3
4
7
11
...

#include <iostream>
#include <vector>
using namespace std;

vector<int> fib(int a=1, int b=2, int max=4000000){
    vector<int> v;
    long sum;
    v.push_back(a);
    v.push_back(b);
    while (a < max){
        sum = 0;
        sum = b + a;
        b = a;
        a = sum;
        v.push_back(sum);

    }
    return v;
}

int main(){
    int total = 0;
    vector<int> v;
    v = fib();
    for (int i=0; i<v.size(); i++){
        cout << v[i] << endl;
        total += v[i];
    }
    cout << "total: " << total << endl;

[vlad from moscow]

Let consider iterations

1) a = 1; v.push_back( a );
2) b = 2; v.push_back( b )
3) sum = 3; v.push_back( sum ); b = a ( b == 1 ); a = sum; ( a == 3 );
4). sum = 4 ( b (== 1 ) + a ( == 3 ) ); ....

[metulburr]

4). sum = 4 ( b (== 1 ) + a ( == 3 ) );

i do not follow

[vlad from moscow]

b is equal to 1, a is equal to 3. Question: What value will have sum?

[metulburr]

yeah but its not suppose to be 4.

grr, C's syntax is driving me nuts.

[vlad from moscow]

What you do is what you get. What is the problem?! I showed you your iterations.

[Smac89]

Inside your while loop should be:

sum = a + v.back();
a = v.back();
v.push_back(sum);