Error: expected type-specifier before 'ClassName'
shared_ptr<Shape> circle(new Circle(Vec2f(0, 0), 0.1, Vec3f(1, 0, 0)));
shared_ptr<Shape> rect(new Rect2f(Vec2f(0, 0), 5.0f, 5.0f, 0,
Vec3f(1.0f, 1.0f, 0)) );
I'm trying to understand why the above won't compile. For Whatever reason, when I try to create an instance of Rect2f (which DOES inherit from the Shape
class specified the shared_ptr
template argument, just like Circle
), I get the following errors:
error: expected type-specifier before 'Rect2f'
error: expected ')' before 'Rect2f'
Everything about the Circle
shared_ptr
is perfectly fine. There are no problems with it; it's only the Rect2f
which is causing issues.
Furthermore, the values passed into the constructor are valid.
So, what could the issue be with this one? I have Rect.h
included for this. For brevity's sake (and incase I missed something in that file which may be affecting this), I'll post the following:
Rect.h
#pragma once
#include <QGLWidget>
#include <GL/glext.h>
#include <cmath>
#include <QDebug>
#include "Shape.h"
#include "Vec3f.h"
#include "rand.h"
const int DEFAULT_SQUARE_WIDTH = 5;
const int DEFAULT_SQUARE_HEIGHT = 5;
typedef enum {
RC_TOPLEFT,
RC_TOPRIGHT,
RC_BOTTOMRIGHT,
RC_BOTTOMLEFT
} RectangleCorner;
class Rect2f : public Shape
{
public:
Rect2f(
Vec2f center = Vec2f(),
float width = 4,
float height = 4,
float radius = 0,
Vec3f color = Vec3f()
);
~Rect2f();
inline const float GetWidth( void ) const {
return mWidth;
}
inline const float GetHeight( void ) const {
return mHeight;
}
inline const Vec2f* GetCorner( RectangleCorner rc ) const {
switch( rc ) {
case RC_TOPLEFT:
return mTopLeftCrnr;
break;
case RC_TOPRIGHT:
return mTopRightCrnr;
break;
case RC_BOTTOMLEFT:
return mBottomLeftCrnr;
break;
case RC_BOTTOMRIGHT:
return mBottomRightCrnr;
break;
}
}
void UpdateCorners();
virtual void Collide( Shape &s );
virtual void Collide( Rect2f &r );
virtual void Collide ( Circle &c );
virtual bool Intersects( const Shape& s ) const;
virtual bool Intersects( const Rect2f& s ) const;
virtual bool IsAlive( void ) const;
virtual float Mass( void ) const;
protected:
virtual void Draw( void ) const;
float mWidth, mHeight;
Vec3f mColor;
private:
Vec2f* mTopLeftCrnr;
Vec2f* mTopRightCrnr;
Vec2f* mBottomLeftCrnr;
Vec2f* mBottomRightCrnr;
};
Source of Error Function and File Header (mainwindow.cpp)
#include "ui_mainwindow.h"
#include "Vec2f.h"
#include "Rect2f.h"
#include "SharedPtr.h"
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi( this );
BoxOfShapes* display = new InteractiveBoxOfShapes( this, 600, 600 );
ui->mGridLayout->addWidget( display );
ui->mStatusBar->showMessage( "status ok" );
QObject::connect( display, SIGNAL( numShapesChanged( int ) ), this, SLOT( setNumShapes(int) ) );
QObject::connect( ui->mResetButton, SIGNAL( pressed() ), display, SLOT( resetWorld() ) );
shared_ptr<Shape> circle(
new Circle(
Vec2f( 0, 0 ),
0.1,
Vec3f( 1, 0, 0 ) ) );
/*std::shared_ptr<Shape> rect( <---error
new Rect2f(
Vec2f( 0, 0 ),
5.0f,
5.0f,
0,
Vec3f( 1.0f, 1.0f, 0 )
)
);*/
shared_ptr< Shape > rect( new Rect2f() ); //error - second attempt
display->addShape( circle );
display->addShape( rect );
}
Main Function Test (main.cpp)
#include <QtGui/QApplication>
#include "mainwindow.h"
#include "Rect2f.h"
int main(int argc, char *argv[])
{
Rect2f rec;
QApplication a(argc, argv);
MainWindow w;
w.show();
return a.exec();
}
Question
Judging from the errors provided, what am I missing here? Also, what can be done to rectify this issue?
For future people struggling with a similar problem, the situation is that the compiler simply cannot find the type you are using (even if your Intelisense can find it).
This can be caused in many ways:
- You forgot to
#include
the header that defines it. - Your inclusion guards (
#ifndef BLAH_H
) are defective (your#ifndef BLAH_H
doesn't match your#define BALH_H
due to a typo or copy+paste mistake). - Your inclusion guards are accidentally used twice (two separate files both using
#define MYHEADER_H
, even if they are in separate directories) - You forgot that you are using a template (eg.
new Vector()
should benew Vector<int>()
) - The compiler is thinking you meant one scope when really you meant another (For example, if you have
NamespaceA::NamespaceB
, AND a<global scope>::NamespaceB
, if you are already withinNamespaceA
, it'll look inNamespaceA::NamespaceB
and not bother checking<global scope>::NamespaceB
) unless you explicitly access it. - You have a name clash (two entities with the same name, such as a class and an enum member).
To explicitly access something in the global namespace, prefix it with ::
, as if the global namespace is a namespace with no name (e.g. ::MyType
or ::MyNamespace::MyType
).
First of all, let's try to make your code a little simpler:
// No need to create a circle unless it is clearly necessary to
// demonstrate the problem
// Your Rect2f defines a default constructor, so let's use it for simplicity.
shared_ptr<Shape> rect(new Rect2f());
Okay, so now we see that the parentheses are clearly balanced. What else could it be? Let's check the following code snippet's error:
int main() {
delete new T();
}
This may seem like weird usage, and it is, but I really hate memory leaks. However, the output does seem useful:
In function 'int main()':
Line 2: error: expected type-specifier before 'T'
Aha! Now we're just left with the error about the parentheses. I can't find what causes that; however, I think you are forgetting to include the file that defines Rect2f
.