Are pointers to pointers legal in c++? I've come across this SO question: Pointer to Pointer to Pointer
But the answers aren't clear if it is legal c++ or not. Let's say I have:
class A{
public:
void foo(){
/* ect */
}
};
class B{
public:
A* a;
/* ect */
};
void Some_Func() {
B *b;
// besides this looking ugly, is it legal c++?
b->a->foo();
};
Is the line b->a->foo()
OK to write? Is there a better way to represent this expression?
This is perfectly valid.But the term you are using " pointer to pointer " is wrong.
the term means a double pointer like **P
, a pointer which holds the address of another pointer .
but your case is the pointer(of class A) is an member of a class whose pointer(of class B) is created by you in some_func
Illegal, "a" is private. So is "foo".
If corrected to "public" then they're legal constructs.
From your code its hard to find a "better" way. BUT You can modify the code to make the code look much clearer:
class A{
public:
void foo(){ cout << "Work";}
};
class B{
private:
A *a;
public:
A& getA(){
return *a;
}
};
void SomeFunction()
{
B *b = new B();
B& bRef = *b;
bRef.getA().foo(); //better looking code?
delete b;
}
It is legal but in your example your program will crash (if you could compile it since your members are private) because you did not create an instance of B
void Some_Func() {
B *b; // uninitialized B ptr should be B* b = new B;
// legal
b->a->foo();
};
Although you may want to reconsider accessing variables directly as you do and instead have getter/setters to access private member variables.
Yes but then you have to use pointer to pointer like **P
.
Actually if we want to access a pointer which is holding another pointer then we can do this.This is allowed in c++ but keep in mind that only in case if you have assigned a pointer to pointer p
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