Question

OpenGL 2D

i asked this question: Line graph using lines and point and i get this answer but when try to run i get error :

[Error] 'drawLine' was not declared in this scope.

[Warning] deprecated conversion from string constant to 'char*' [-Wwrite-strings] .

#include<math.h>
#include"graphics.h

const int width=800,height=600;
int drawline(int movetoX, int movetoY, int drawX, int drawY, int textX, int textY, int colour, char *name)
{
   moveto(movetoX,movetoY);
   setcolour(colour);
   lineto(drawX,drawY);
   outtextxy(textX,textY,name);
}

int main(){
   double x,y;
   initwindow(width,height);
   moveto(height/2,width/2); //move cursor to centre
  
   // let us draw first function
   for(x=0;x<width;x+=0.01)
   {
       y=pow(x,4);
       setcolour(14);
       lineto(width/2+(x*100),height/2-(y*100));
   }
  
   // let us draw first function
   for(x=0;x<width;x+=0.01)
   {
       y=pow(x,1./3.);
       lineto(width/2+(x*100),height/2-(y*100));
   }
  
   //and our x and y lines are:
   drawLine(0,height/2,width,height/2,WHITE,width-20,height/2+10,"x");
   drawLine(width/2,0,width/2,height,WHITE,width/2+10,0,"y");
  
  
   getch();
   closegraph();
   system("PAUSE");
   return 0;
  
}

//Use this code in Dev-c++ (4.9.9.2)

#include<math.h>
#include"graphics.h

const int width=800,height=600;
int drawline(int movetoX, int movetoY, int drawX, int drawY, int textX, int textY, int colour, char *name)
{
   moveto(movetoX,movetoY);
   setcolour(colour);
   lineto(drawX,drawY);
   outtextxy(textX,textY,name);
}

int main(){
   double x,y;
   initwindow(width,height);
   moveto(height/2,width/2); //move cursor to centre
  
   // let us draw first function
   for(x=0;x<width;x+=0.01)
   {
       y=pow(x,4);
       setcolour(14);
       lineto(width/2+(x*100),height/2-(y*100));
   }
  
   // let us draw first function
   for(x=0;x<width;x+=0.01)
   {
       y=pow(x,1./3.);
       lineto(width/2+(x*100),height/2-(y*100));
   }
  
   //and our x and y lines are:
   drawLine(0,height/2,width,height/2,WHITE,width-20,height/2+10,"x");
   drawLine(width/2,0,width/2,height,WHITE,width/2+10,0,"y");
  
  
   getch();
   closegraph();
   system("PAUSE");
   return 0;
  
}

//Use this code in Dev-c++ (4.9.9.2)

Answer 1

Change the below lines in main()
   drawLine(0,height/2,width,height/2,WHITE,width-20,height/2+10,"x");
   drawLine(width/2,0,width/2,height,WHITE,width/2+10,0,"y");

to

drawline(0,height/2,width,height/2,WHITE,width-20,height/2+10,"x");
drawline(width/2,0,width/2,height,WHITE,width/2+10,0,"y");

the function is drawline() -> small l in line but you are calling drawLine() -> capital L , remember C/C++ is a type sensitive language and so you must take care of small and capital letters as they are treated differently.

So drawline() and drawLine() are two different functions of which only drawline() is defined in your program not drawLine() , so you are getting the error 'drawLine' was not declared in this scope.