<vector> and new

[wysota]

The vector will clear itself when it's destructed so an explicit clear() is not necessary (and remember clear() doesn't free the memory occupied by items stored in the vector).

[mickey]

Sorry I've still compile problem; the first compile (and seem works too), the 2th no;Why? What is happening?

class Scene {
  std::vector<Light> light;
};
 
Scene::Scene() {
    light.push_back(Light()); 
}
 
Scene::~Scene() {
    light.clear(); 
}

class Scene {
  std::vector<Light> light;
};

Scene::Scene() {
    light.push_back(Light()); 
}

Scene::~Scene() {
    light.clear(); 
}

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class Scene {
  std::vector<Light> light(1); //with (1) don't compile
};
 
Scene::Scene() {
    light.push_back(Light()); 
}
 
Scene::~Scene() {
    light.clear(); 
}

class Scene {
  std::vector<Light> light(1); //with (1) don't compile
};

Scene::Scene() {
    light.push_back(Light()); 
}

Scene::~Scene() {
    light.clear(); 
}

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qsignalslotimp.h(66): fatal error C1903: unable to recover from previous error(s); stopping compilation
mainform.ui.h(75): error C2109: subscript requires array or pointer type
mainform.ui.h(75): error C2228: left of '.getPosition' must have class/struct/union type
mainform.ui.h(75): error C2475: 'Scene::light' : forming a pointer-to-member requires explicit use of the address-of operator ('&') and a qualified name
mainform.ui.h(75): error C2475: 'Scene::light' : forming a pointer-to-member requires explicit use of the address-of operator ('&') and a qualified name
mainform.ui.h(959): error C2109: subscript requires array or pointer type
mainform.ui.h(959): error C2228: left of '.setXPosition' must have class/struct/union type
..........................................

qsignalslotimp.h(66): fatal error C1903: unable to recover from previous error(s); stopping compilation
mainform.ui.h(75): error C2109: subscript requires array or pointer type
mainform.ui.h(75): error C2228: left of '.getPosition' must have class/struct/union type
mainform.ui.h(75): error C2475: 'Scene::light' : forming a pointer-to-member requires explicit use of the address-of operator ('&') and a qualified name
mainform.ui.h(75): error C2475: 'Scene::light' : forming a pointer-to-member requires explicit use of the address-of operator ('&') and a qualified name
mainform.ui.h(959): error C2109: subscript requires array or pointer type
mainform.ui.h(959): error C2228: left of '.setXPosition' must have class/struct/union type
..........................................

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[jacek]

It should be:

class Scene 
{
  public:
     Scene();
     // ...
  private:
     std::vector<Light> light;
};
 
Scene::Scene() : light(1) 
{
   // ...
}

class Scene 
{
  public:
     Scene();
     // ...
  private:
     std::vector<Light> light;
};

Scene::Scene() : light(1) 
{
   // ...
}

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[mickey]

OK It works! but I don't understand where's the problem in my solutions.. Can't I give dimension of vector inside class? thanks

[jacek]

Can't I give dimension of vector inside class?

No, you can't. You can only declare member variables there.