Quick question on using the constructer with multiple files.

Question

Hi there, I have this class header

//header for class.
#ifndef Container_H
#define Container_H

#include <iostream>
using namespace std;


const int DEFAULT=32;

class Container{
    public:
        Container(int maxCapacity = DEFAULT);
        ~Container();
        void insert(int item, int index);
        void erase(int index);
        int size()const;
    private:
        int sizeC;                
        int capacityC;           
        int * elements;            
};
void info();
#endif

and this source file

#include "container.h"


Container::Container(int maxCapacity = DEFAULT){
    int y;
}
void Container::insert(int item, int index){
    int x;
}

and when i compile this i get the following error message

test.cpp:4: error: default argument given for parameter 1 of `Container::Container(int)'
container.h:12: error: after previous specification in `Container::Container(int)

what have i done wrong here?

Answer 1

Functions with no arguments still need the parentheses:

Container::Container() {
    int y;
}

Based on your header, it looks like you just forgot the maxCapacity argument, and it should actually be:

Container::Container(int maxCapacity) {
    int y;
}

(If you're asking about the warning too, it's pretty self-evident -- you declared an int x but didn't do anything with it)

EDIT: Well now you've edited it to completely change the error. Now it's an error because you're specifying the default argument in both places; you're only supposed to specify it in the declaration. Leave it out in the actual implementation, like my second example above

Answer 2

Container::Container{ int y; } is syntactically incorrect.

EDIT:

Try this:

Container::Container(int maxCapacity) // default argument not to be mentioned in the definition
{
  int y;
}

Answer 3

Your Container constructor (in the source file) should be like this:

Container::Container(int maxCapacity){
    // code
}

Answer 4

Container::Container{
    int y;
}

I'm not sure what this is intended to be. If you're trying to define your ctor, it should look something like:

Container::Container(int maxCapacity) // ....

Note that you want to include the default value in the declaration, but not in the definition.