C / C++ / MFC

for (int loop=0; loop<2; loop++)									// Loop To Draw Our 4 Views
	{
		if (loop==0)													// If We Are Drawing The First Scene
		{
			m_bRenderFromVideo=FALSE;
			if(m_pbVideoData)
				gluBuild2DMipmaps(GL_TEXTURE_2D, 3, m_iVideoHeight,m_iVideoWidth ,GL_LUMINANCE, GL_UNSIGNED_BYTE, m_pbVideoData);

			glViewport(m_iNoOfColumn - m_iNoOfColumn * m_iSizeVideo.x, m_iNoOfRow - m_iNoOfRow * m_iSizeVideo.y, 
			m_iNoOfColumn * m_iSizeVideo.x, m_iNoOfRow * m_iSizeVideo.y);
			glPushMatrix();

			gluOrtho2D(-window_width/4, window_width/4, -window_height/4, window_height/4);
			//glDrawPixels( window_width/2,  window_height/2, GL_LUMINANCE,GL_UNSIGNED_BYTE, (void*)m_pbVideoData);
			glLoadIdentity ();											// Reset The Projection Matrix

			glDisable(GL_TEXTURE_GEN_S);								// Enable Texture Coord Generation For S (NEW)
			glDisable(GL_TEXTURE_GEN_T);								// Enable Texture Coord Generation For T (NEW)

			glDisable(GL_LIGHTING);
			glBegin(GL_QUADS);											// Begin Drawing A Single Quad
			// We Fill The Entire 1/4 Section With A Single Textured Quad.
		
			glTexCoord2f(1.0f, 1.0f); glVertex3f( 21.0f,  18.3f, -10.0f);
			glTexCoord2f(0.0f, 1.0f); glVertex3f(-21.0f,  18.3f, -10.0f);
			glTexCoord2f(0.0f, 0.0f); glVertex3f(-21.0f, -18.3f, -10.0f);
			glTexCoord2f(1.0f, 0.0f); glVertex3f( 21.0f, -18.3f, -10.0f);
			glEnd();	

			glScalef(m_fScale, m_fScale, m_fScale);
			glRotated(m_fRAngle[0],0.0, 0.0,1.0);
			//glRotated(0,0.0,0.0, m_fRAngle[0]);
			//glRotated(0,0.0,0.0,m_fRAngle[0]);	   

			
		}
		else		
		{
			glPushMatrix();
			glViewport(0, 0, window_width, window_height);
			//float len = 28.0f;			
			//glMatrixMode(GL_PROJECTION);
			glLoadIdentity();
		//	glOrtho(-len, len, -len, len, -len*100.0f, len*100.0f);	
		//	glMatrixMode(GL_MODELVIEW);

			glScalef(m_fScale, m_fScale, m_fScale);
			glRotated(m_fRAngle[0],1.0, 0.0, 0.0);
			glRotated(m_fRAngle[1],0.0,1.0, 0.0);
			glRotated(m_fRAngle[2],0.0,0.0,1.0);	   


		}
		
		
	}	

struct A;
struct B;

struct A
{
  int lolipops;
  B* candy;

  A(B* ptr)
  {
   lolipops = 0;
   candy = ptr;
  }

  action(int pass)
  {
    candy->gums = pass;//this is where i get the error of undefined type 'B'
  }
};

struct B{
 int gums;
 A* candy;
 
 B(A* ptr)
 {
  gums = 0;
  candy = ptr;
 }

 action(int pass)
 {
   candy->lolipops = pass;//this is where i get the error of undefined type 'A'
 }
};