Call by reference using pointers.

[alnews]

Hi guys,
I was wondering, what is the difference in practice between a "normal" call by reference and a call by reference made using pointers as arguments? Why one of the two should be prefered over the other? Thank you.

[helios]

References ensure that the parameter is valid. Pointers allow passing null parameters.
Also, a function that takes a const T & can take the return value of a function call as a parameter without making a copy. For example:

std::string f(){
    return "string";
}

void g(const std::string &s){
    std::cout <<s;
}
//...
g(f());