I am trying to dynamically allocate a array inside a class. Came across a very weird thing. Please have look on this two piece of code and do tell me the difference.
class A{
public:
int n;
int *a;
a = new int [4];
~A(){delete []a;}
A(){}
}
Compiling with GCC produces the following error:
a does not a name type
But when I use:
class A{
public:
int n;
int *a = new int [4];
A(){}
~A(){ delete []a;}
}
It compiles
a= new int [4];
Is not an initialization but an assignment and is not allowed.
int *a = new int [4];
Works as it is an in class initilization and is allowed in C++11 and beyond.
You are also mixing new[] and delete. Whenever you use new you should have a call to delete and when you use new[] you need to call delete[]
Now instead of dealing with pointers and new[] and delete[] you should use a std::vector instead.
This is an initialization:
int *a = new int [4];
This is an assignment which can't be done in a class declaration, but can be done, e.g., in a constructor:
a = new int [4];
Also, if you use new[], you also need to use delete[], not delete.
I'm not clear on what exactly you're shooting for, but this work should be done in the constructor and destructor of the class
class A
{
public:
A() { a = new int[4]; }
~A() { delete[] a; }
private:
int* a;
};
and better yet, you could avoid doing any dynamic allocation yourself if you use std::vector
class A
{
public:
A() : a(4) {}
private:
std::vector<int> a;
};
