Hello,

I am having trouble trying to set up my physics class in C++ using Box2D. Every time I try to set the World variable to the Gravity variable, I keep getting this error, 1 IntelliSense: no instance of constructor "b2World::b2World" matches the argument list
argument types are: (b2Vec2 *, bool)

I assume, there is something wrong with converting the variables, but I can't exactly pinpoint it. I'll post my code.

//Physics.CPP
#include "main.h"
#include "physics.h"

Physics::Physics()
{
	X_Grav = 0.0f;
	Y_Grav -= 10.0f;
	Sleep = true;

	Gravity = new b2Vec2(X_Grav,Y_Grav);
	World = new b2World(Gravity,Sleep); //error comes from this
}

//Physics.h
class Physics
{
public:
	Physics();
	~Physics();

	b2Vec2* Gravity;
	b2World* World;

	bool Sleep;

This is only some of the code, I think it is enough to help figure out what the problem is. I can post more code if it is needed. Thanks.

No, it does not compile, here is the error from trying to compile Error 1 error C2664: 'b2World::b2World(const b2Vec2 &)' : cannot convert parameter 1 from 'b2Vec2 *' to 'const b2Vec2 &'

It sounds like the constructor for b2World is expecting an actual value (a constant reference), and not a pointer, which is what you are passing in.

EDIT: To test, just stick a * in front of the variable:

World = new b2World(*Gravity,Sleep);

class Foobar {
public:
    Foobar(int id) {
        a = id;
        ptr = new char[15];
    }

    Foobar( const Foobar& other ) { // copy constructor
        this->a = other.a;
        this->ptr = new char[15];
    }

    Foobar& operator= ( const Foobar& other ) { // assignment (copy)
        this->a = other.a;
        delete[] this->ptr;
        this->ptr = new char[15];

        return *this;
    }

    ~Foobar() {
        delete[] ptr;
    }

private:
    int a;
    char* ptr;
};

int main() {
    Foobar A(1);        // A is a valid Foobar (resides on the stack)
    Foobar& B = A;      // B *is* A
    Foobar* C = &A;     // C is a pointer to A
    Foobar D(A);        // D is a copy of A (uses copy constructor)

    C = &D;             // C now points to D
    B = D;              // A is now a copy of D (uses assignment operator, cannot reassign references)

    Foobar* E = new Foobar(3); // create a new Foobar (residing on the freestore), assign it to E
    C = E;              // C and E refer to the same Foobar
                            
    delete C;           // destroy Foobar #3
    E = 0;              // E still refers to deleted Foobar #3, set to nullptr/NULL/0 to prevent accidental access
}

Ah, I see. That makes sense. Thank you.