the value of a varaiable in a function

[lythedan]

This is the simplest problem from a bigger question. The simplified question is finding the size of a dividing chain from a 4-number chain, starting by the first number of the 4-number chain. As I said, I focus on the simplest case, for example:

Input: chain: 1,2,3,4
Output: 3 (size of chain:1,2,4). (Another chains are "1,3" or "1,4", but we don't mention, because finding them is easy if we can show the simplest "1,2,4").

Input: chain: 3,4,5,7
Output: 1 (size of chain:3)

Here is my code:

#include<iostream>
using namespace std;
int result(int a[4], int &count, int &start);
int main(){
       int a[4];
       for (int i=0; i<4; i++){
           cin>>a[i];
       }//getting input

       int count=1;
       int start=0;
       cout<<"result showed by function: "<<result(a,count,start)<<endl;
       cout<<"the value of count: "<<count<<endl;
       system("pause");
       return(0);
}

int result(int a[4], int &count, int &start){
    //cout<<"start: "<<start<<endl;
    if (start==3) return count;
    
    for (int i=start+1; i<4;i++){
        if (a[i]%a[start] ==0){
           count++;
           //cout<<"a["<<i<<"]:"<<a[i]<<endl;
           //cout<<"count: "<<count<<endl;
           start =i;
           break;
        }
        if (i==3) return count;//no remained appropriate value for the chain
    }
    result(a,count,start);
}

With the input chain: 1,2,3,4 , as you see, the value of "count" is 3, the right answer. But the result of function "result" is a strange value, even though it is returned by "count". The similar result happens with input chain: 3,4,5,7. Any one who can tell me the problem? Thanks.

[chrisname]

What? I'm not sure what you're trying to do.

So you have a four-element array that you pass to result. Then you pass count to result (which, in your code, thinks it is getting a memory reference) and do the same with start. Then you expect

Read this: http://cplusplus.com/doc/tutorial/pointers/
particularly about the reference operator.

#include<iostream>
using namespace std;
int result(int a[4], int count, int start); /* These should be normal integers. 
                                                         Why are you putting the reference operator there? */
int main(){
       int a[4];
       for (int i=0; i<4; i++){
           cin>>a[i];
       }//getting input

       int count=1;
       int start=0;
       cout<<"result showed by function: "<<result(a,count,start)<< "\n";
       cout<<"the value of count: "<<count<< "\n"; // Buffer doesn't need to be flushed
       // std::cout << std::endl == std::cout << "\n" << std::flush; you don't need to flush the buffer.
       std::cin.ignore();
       std::cin.get() // Do NOT use system()
       return(0);
}

int result(int a[4], int count, int start){
    cout<<"start: "<<start<<endl;
    if (start==3) return count;

    for (int i=start+1; i<4;i++){
        if (a[i]%a[start] ==0){
           count++;
           cout<<"a["<<i<<"]:"<<a[i]<<endl;
           cout<<"count: "<<count<<endl;
           start =i;
           break;
        }
        if (i==3) return count;//no remained appropriate value for the chain
    }
    result(a,count,start); // Why is this recursing???
}

I really don't see what you're trying to do in result...

[jsmith]

Line 35

return result( a, count, start );