Help with a compiler error

[LarryChen]

Here is the code,

class A
{
public:
	A(int* p)
	{
		ptr(p);
	}

private:
	int* ptr;
};

There is a compiler error "error C2064: term does not evaluate to a function taking 1 arguments" from the statement ptr(p) . I wander why?

[ZuK]

A(int* p)
  :ptr(p){
}

[Speedo]

Here is the code,

class A
{
public:
	A(int* p)
	{
		ptr(p);
	}

private:
	int* ptr;
};

There is a compiler error "error C2064: term does not evaluate to a function taking 1 arguments" from the statement ptr(p) . I wander why?

ptr(p) is either a function call, or the creation of a temporary object of type ptr which has a ctor taking an int*. The compiler can't find a match for either. If you intended to use an initialization list, look at ZuK's post. Otherwise you need to do ptr = p.

[LarryChen]

According to the same reasoning, we can't put the statement ptr(p) in a initialization list either. Then why can we put the same statement in initialization list? Thanks.

ptr(p) is either a function call, or the creation of a temporary object of type ptr which has a ctor taking an int*. The compiler can't find a match for either. If you intended to use an initialization list, look at ZuK's post. Otherwise you need to do ptr = p.

[Paul McKenzie]

According to the same reasoning, we can't put the statement ptr(p) in a initialization list either.

A computer language has syntax, and a lot of the rules of the syntax deals with context.

In the context of a function block, that ptr(p) means one thing, in the context of an initialization list, it means another. If the rules of C++ are expanded in the future, maybe ptr(p) means something else within that new context. You can't use "reasoning" here -- those are the rules of the language.

Regards,

Paul McKenzie