[英]Static function access to class member
班级标题:
#ifndef _APP_H_
#define _APP_H_
#include "glut.h"
#include "Declare.h"
class App {
private:
static float angle;
public:
App();
int OnExecute();
void OnLoop();
static void OnRender();
bool OnInit();
void OnCleanup();
static void OnResize(int w, int h);
};
#endif
我对OnRender的定义是
#include "App.h"
App::App() {
angle = 0.0f;
}
void App::OnRender() {
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
gluLookAt( 0.0f, 0.0f, 10.0f,
0.0f, 0.0f, 0.0f,
0.0f, 1.0f, 0.0f);
glRotatef(angle, 0.0f, 1.0f, 0.0f);
glBegin(GL_TRIANGLES);
glVertex3f(-2.0f,-2.0f,0.0f);
glVertex3f(2.0f,0.0f,0.0f);
glVertex3f(0.0f,2.0f,0.0f);
glEnd();
angle+=0.1f;
glutSwapBuffers();
}
错误:
1>App.obj : error LNK2001: unresolved external symbol "private: static float App::angle" (?angle@App@@0MA)
1>App_OnRender.obj : error LNK2019: unresolved external symbol "private: static float App::angle" (?angle@App@@0MA) referenced in function "public: static void __cdecl App::OnRender(void)" (?OnRender@App@@SAXXZ)
与我如何在静态函数中引用静态变量有关。 如果我没有将角度声明为static float angle
那么我当然无法通过static void OnRender()
来访问它。 我必须添加更多细节。 如果我没有声明它是静态的,我得到这个错误illegal reference to non-static member App::angle
在源文件App.cpp
您需要定义静态变量:
static float App::angle = 0; //0 is my test default value. use yours
如果要在非静态方法中使用angle
, 可能需要将类实例与App:angle
。 例如 :
App::App() {
App::angle = 0.0f;
}
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