Vector with multiple class objects yields a compilation error?

Question

For the following class I wanted to make a vector with 10 Ship() objects
However this yields the following compilation error invalid conversion from 'int' to 'const char*' [-fpermissive]
( If I omit the vector line it compiles just fine)
I did a little search and could not find an answer.

class Ship
{

protected:
        std::string name;
public:
        Ship(std::string name="Ship")
        {
          std::ostringstream tmp;
          std::string temp;
          tmp << name << ++id;
          name = tmp.str();
        }
};

Vector Declaration in main()

#include <iostream>
#include <vector>
#include <string>
#include "Ship.h"
using std::cout;
using std::endl;
using std::vector;
int main()
{
     vector<Ship> Shipyard; //10% of map dimension is number of ships
     Shipyard.push_back(Ship(10)); //push_back(Ship(),10); doesn't work also
}

PaulMcKenzie · Answer 1 · 2014-11-15T17:12:23.783

1

You are constructing a Ship object with the value of 10. Since the constructor takes std::string, you cannot pass an integer to the constructor.

To add 10 ships:

std::vector<Ship> ShipYard(10);

or

std::vector<Ship> ShipYard;
ShipYard.resize(10);

edited Nov 15 '14 at 17:12

answered Nov 15 '14 at 17:06

PaulMcKenzie

34,698
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thanks however I can't find nowhere how to add 10 objects of Ship() constructor in one line (not manually) – solid.py Nov 15 '14 at 17:07
1

Please see the updated answer. You are looking for `resize()`, not `push_back`. – PaulMcKenzie Nov 15 '14 at 17:14
I added resize() however how to call Ship() for every vector element (I suppose that after resize it has nothing right?) – solid.py Nov 15 '14 at 17:18
The `resize` will default construct 10 Ship objects. – PaulMcKenzie Nov 15 '14 at 17:42
it yields this compiler error undefined reference to `vtable for Ship' (and shows me the Ship constructor line) – solid.py Nov 15 '14 at 17:45
@niCk - You are not posting your entire code. The code at the link compiles with no errors: http://ideone.com/viuFeK – PaulMcKenzie Nov 15 '14 at 18:13
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/65004/discussion-between-nick-and-paulmckenzie). – solid.py Nov 15 '14 at 18:15
I have 2 virtual methods Should I edit? Their bodies are defined separately in subclasses – solid.py Nov 15 '14 at 18:17

P0W · Accepted Answer · 2014-11-15T17:13:50.907

1

The constructor takes a std::string, but you're passing an integer

For 10 objects construction of same name use this 2nd form of constructor of std::vector :

vector<Ship> Shipyard( 10, Ship() );

edited Nov 15 '14 at 17:13

answered Nov 15 '14 at 17:08

P0W

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vector Shipyard; Shipyard.push_back(10,Ship()); is identical? (because this one yields error) – solid.py Nov 15 '14 at 17:09
no matching function for call to 'std::vector::push_back(int, Ship)' – solid.py Nov 15 '14 at 17:12
@niCk Did you read the my entire post correctly, I didn't use `push_back`. You just have to use the appropriate constructor – P0W Nov 15 '14 at 17:15
This line of code vector Shipyard( 10, Ship() ); yields this error:Undefined reference to 'vtable for Ship' – solid.py Nov 15 '14 at 17:15
I read your entire post I just asked for push_back identical syntax but its ok leave it, I deleted the push_back line – solid.py Nov 15 '14 at 17:17
@nick Now, this current error is unrelated to your current question, you need to provide more details. Please see [this](http://stackoverflow.com/q/1095298/1870232) post – P0W Nov 15 '14 at 17:21
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/65003/discussion-between-nick-and-p0w). – solid.py Nov 15 '14 at 17:42

score 1 · Answer 3 · answered Nov 15 '14 at 17:09

1

Ship(10)

This will try to create one Ship object and call the constructor. However your constructor take string as argument and hence the error.

To create vector of 10 Ships use:

vector<Ship> Shipyard(10, Ship());

answered Nov 15 '14 at 17:09

rockoder

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Vector with multiple class objects yields a compilation error?

3 Answers3