Question

I have a function that writes things from a binary tree. When I run it, it just writes the root of the tree in the txt. can someone tell me what is wrong here?

void tree::wrte(person *p)
{
    ofstream out("myfile.txt");

    struct register{
        char ID[15];    
        char name[30];      
        char surname[30];       
    };                              

    register reg;   
    if(!(mybook=fopen("myfile.txt","a+")))
    {                           
        if (!(mybook=fopen("myfile.txt","w+")))
        {                                             
            cerr<<"Couldnt opened"<<endl;return;                  
        }                                                                
    }                                          
    if(p)                   
    {                               
        strcpy(reg.name,p->name);               
        strcpy(reg.ID,p->ID);                           
        strcpy(reg.surname,p->surname);                         
        out << reg.ID <<'\t'<<reg.name<<'\t'<<reg.surname<<'\t'<<endl;  
        wrte(p->left);                                                          
        wrte(p->right);                                                                 
    }                                                                                       
    out.close();                
}

Answer 1

If you really must open the file each time you call wrte(), I’d change the code to close the current stream before recursively calling write again:

if(p)
{
    ...
    out << reg.ID <<'\t'<<reg.name<<'\t'<<reg.surname<<'\t'<<endl;
    out.close();
    wrte(p->left);
    wrte(p->right);
    ...

However, a better design would be to pass an ostream to your wrte() function:

void tree::wrte(ostream& out, person *p){
    ...
    if(p)
    {
        ...
        out << reg.ID <<'\t'<<reg.name<<'\t'<<reg.surname<<'\t'<<endl;
        wrte(out, p->left);
        wrte(out, p->right);
    }
    ...
}

Then open the output stream before your first invocation of wrte():

int main()
{
    ...
    ofstream out("myfile.txt");

    ...
    tree_ptr->wrte(out, p);
    out.close();
    ...
}