CODEWITHSUNDEEP
c++
user3316811
user3316811

Reputation:

c++ error when requesting member function

I have a class like so

class action {
    int val;
    // some other members
public:
    action()        : val(0)   { } // default constructor initializes action type to 0
    action(int val) : val(val) { } 
    // some other member functions
    int getVal() { return val; }
};

and when used in a simple scenario

action obj1(), obj2(2);
cout << "Initial state : { " << obj1.getVal() << ", " << obj2.getVal() << " }\n";

I get a compilation error 

error: request for member ‘getVal’ in ‘obj1’

What is going on here?

Upvotes: 3

Views: 94

Answers (5)

Vlad from Moscow
Vlad from Moscow

Reputation: 310920

In this statement

action obj1(), obj2(2);

you declared function 

action obj1()

that has return type action and has no parameters and an object of type action

action obj2(2);

Change this statement to

action obj1, obj2(2);

The other way to avoid such an error is to write

action obj1 {}, obj2(2);

provided that your compiler supports the list initialization.

The problem is that there is an ambiguity between function declarations and object definitions with empty lists of arguments. C++ resolves the conflict for benefit of function declarations.

Upvotes: 0

venkysmarty
venkysmarty

Reputation: 11431

To fix above mentioned error remove () in obj1 while declaring.

Upvotes: 0

Waqar Ahmed
Waqar Ahmed

Reputation: 5068

replace obj1() with obj1. it will work

Upvotes: 1

Nikos Athanasiou
Nikos Athanasiou

Reputation: 31489

That's because you are not declaring an obj1 of type action

action obj1()

declares a function obj1 that takes no parameters and returns an action object. Prefer the c++11 brace initialization to call default constructor

action obj1{}

or just don't use those extra parentheses.

You can google for this issue, as c++ most vexing parse

Upvotes: 3

Some programmer dude
Some programmer dude

Reputation: 409136

It's because the declaration

action obj1();

actually declares obj1 to be a function which returns an action object. Unless you need to pass arguments to the constructor, drop the parentheses:

action obj1;

Upvotes: 3

Related Questions