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#include<math.h>
#include<iostream.h>
#include<graphics.h>
#include <conio.h>
 
void LINE(int x1, int y1, int x2, int y2)
{
int x=x1;
int y=y1;
 
int dx=abs(x2-x1);
int dy=abs(y2-y1);
 
int Sx=abs(x2-x1)/(x2-x1);  //Sign
int Sy=abs(y2-y1)/(x2-x1);
 
int steps,flag;
 
//Determining Greater length
if(dy > dx)
{
steps=dy;
flag=1;
 
//Swapping dx dy
int t=dx;
dx=dy;
dy=t;
}
else
{
steps=dx;
flag=0;
}
 
//Decision variable
int P=2*dy-dx;
 
//First Pixel
putpixel(x,y,WHITE);
 
//Other Pixels:
for(int i=1; i<=steps; i++)
{
 
while( P > 0 )
{
 
if(flag==1)
x=x+Sx;
else
y=y+Sy;
 
P=P-2*dx;
} //END OF WHILE
 
if(flag==1)
y=y+Sy;
else
x=x+Sx;
 
P=P+2*dy;
 
putpixel(x,y,WHITE);
 
} //END OF FOR
 
}
 
 
 
void main()
{
int gdriver=DETECT, gmode;
initgraph(&gdriver, &gmode, "C:/TC/BGI");
 
int x1,x2,y1,y2;
setbkcolor(DARKGRAY);
setcolor(WHITE);
 
cout<<"\n Enter the Initial X Y Coordinate: ";
cin>>x1>>y1;
 
cout<<"\n Enter the Final X Y Coordinate: ";
cin>>x2>>y2;
 
cout<<"\n Press Enter to draw line.";
getch();
 
outtextxy(x1-10,y1-10, "START");
LINE(x1,y1,x2,y2);
outtextxy(x2+10,y2+10, "END");
getch();
closegraph();
}