function returning a pointer to a nest struct

[simone1988]

Hi. I was trying to build a function that takes a numeric array as input and returns the address of a struct representing a pile with the array values "piled up". The code compiles fine, but it does not print the expected result.

I have tried searching the web for "nested structs", "struct pointers", "functions returning struct pointers", but I haven't found anything useful.

Is there a way to fix this program?

The code is this.

#include <iostream>
#include <string>
 
//definition of the struct
struct structure{
    int number;
    structure *next;
};

// definition of the function that should pile up the vector, that is vector[0] is assigned to 
// pile->number, where pile is the output of the function, vector[1] is assigned to
// pile->next->number and so on...
structure* pile_up_vector(int *vector, int vector_size)
{
    int index = 0;
    structure *pile = new structure; //this will be the output
    structure *pile_iterator;
    pile_iterator = pile; // pile_iterator iterates all the nexts and assigns   
                          // the value of number of each struct the value 
                          // vector[i]
    if (vector_size == 0) return 0;
    else
    {
        do
        {
            if(index != 0) pile_iterator = new structure;
            pile_iterator->number = vector[index];
            pile_iterator = pile_iterator->next;
            index = index+1;
        }
        while (index < vector_size);
    }
    return pile; // pointer of the whole struct is returned
}
 
int main()
{
    int vector_size = 3;
    int *vector = new int[vector_size];
    structure *pile;
    int index;
    // initialize vector with 3, 4, 5
    for (index=0; index < vector_size; index++){
        vector[index]=index+3;
    }
    // construction of the pile with the values of vector piled up through pile_up_vector
    pile = pile_up_vector(vector, vector_size);
    // print the values in the structs
    if (pile == 0) std::cout << "null structure" << std::endl;
    else
    {
        for (index = 0; index < vector_size; index++)
        {
            std::cout << pile->number << std::endl;
            if (pile->next == 0) std::cout << "next structure is null" << std::endl;
            else pile = pile->next;
        } 
    }
}

This program prints 3, and then other two random numbers.

[Peter87]

You never set the next pointers to point anywhere so the chain is broken already after the first node.

[simone1988]

Ok. Now, it works. Thank you very much!!