I have a lib.h, lib.cpp and test.cpp. I would like to ask what is better? lib.h
class c
{
std::string name;
}*cc;
lib.cpp
{
std::cout << "the name is:" << name << std:: endl;
}
test.cpp
main()
{
c tst;
tst.name="diana";
}
What should I use? std::string name or std::string *name? How can i work with &name, how will my code change and which one of these 2 methods is the best one?
First, I hardly believe your code will compile while in your main you try to get access to private data member name.
About &. It is really hard to define where to start. In short std::string &name is called reference to object of type std::string. Reference is somehow an alias to some other object. The main feature is, that you always have to initialize refence to object while creating and you can't reinitialize reference to point to another object. More about this feature you can read in C++ FAQ
EDIT Generally you can declare public, protected and private members of your class in with arbitrary ordering:
class MyClass {
//here goes private members when working with class
//and public when working with structs
public:
//here goes public members
protected:
//here goes protected
private:
//here goes private
public:
//here goes public again
};
Ordering of members declaration is actually code policy question. For example, google style guide recommends to put all public members before private.
About hiding function members (not necessary private). You actually can't hide function member declaration, but there are several ways to "hide" implementation, but I am not sure that it's the definition of hiding you are talking about. But you can check PImpl idiom. This requires understanding of pointers so I advice you to start with them first.
Small code sample for working with pointer to string:
#include <iostream>
#include <string>
class MyClass {
public:
std::string *pstr;
};
int main() {
std::string str("test");
MyClass myObj;
myObj.pstr = &str;
std::cout << myObj.pstr->c_str() << std::endl;
}
class MyClass {public: /**/};. But if you want to have the whole class public consider using struct instead of class. struct members are public by default.std::string & name; is a reference. You'll need to initialize it in the constructor, so it actually refers to something. What it refers to must exist as long as your c instance exists. It's not the right solution for this.
std::string name; is an actual variable, use this.
std::string &name is "only" a reference to a string (a bit like a pointer). Because the name definitely belongs to the class c, I think it would make sense to have an instance there.
References are put to good use when passing instances around (to avoid copying).
const std::string&
is reference to a std::string, it is very important to understand the implications of that with respect to the lifetime of variables. Once the referenced variable goes away, the reference is no longer valid, and this is a very common way to f*ck up for beginning C++ programmers.
YMMV, Pick up a good tutorial first, and meanwhile, don't use references unless you know why and what you're doing
Good luck
I'd use: string name; because string* name is just a pointer that needs to be given a value, and then I'd have to think of a way to clean it up later all by myself, and string& name, would be just a name that again has to be initialized.
ccas a pointer toc?)mainfunction you try to modify private membername.