C++ allocating dynamic memory in a function - newbie question

Question

I\'m investigating a memory leak and from what I see, the problem looks like this:

int main(){
    char *cp = 0;
    func(cp);
    //code
    delete[] cp;
}

voi         


        

Answer 1

Although references are wonderful in offering an intuitive abstraction, enhanced further by C++11 rvalue references to allow function chaining (and other esoteric coding), it is arguable that they provide any safety (viz why is a reference considered safer than a pointer) There are instances where it is better to resolve the above with a pointer to pointer function argument. Specifically when there is the need to maintain a similar codebase in ansi c and c++.

#include 

using namespace std;

void func(char ** cp) {
    *cp = new char[100];
    //do something useful
    (*cp)[0] = 'A';
}

void func(char *& cp) {
    cp = new char[100];
    //do something useful
    cp[0] = 'B';
}

int main(int argc, char** argv) {
    char * cp;
    //pointer to pointer
    func(&cp);
    cout << "Index 0 : " << cp[0] << '\n' << flush;
    delete[] cp; //remember to delete!!
    //pointer to ref
    func(cp);
    cout << "Index 0: " << cp[0] << '\n' << flush;
    delete[] cp;
    return 0;
}

Of course the disposal of memory resources out of the scope of the instatiating function disobeys RAII.