Write a C program to check if all the three points fall on one straight line.

#include <stdio.h>
#include <conio.h>
  main()
{
  int x1,y1,x2,y2,x3,y3,x4,y4,slope1,slope2;
  clrscr();
  printf("\n Enter 1st co-ordinate (x1,y1)");
  scanf("\n %d%d",&x1,&y1);
  printf("\n Enter 2nd co-ordinate (x2,y2)");
  scanf("\n %d%d",&x2,&y2);
  printf("\n Enter 3rd co-ordinate (x3,y3)");
  scanf("\n %d%d",&x3,&y3);
  slope1=(y2-y1)/(x2-x1);
  slope2=(y3-y2)/(x3-x2);
  if(slope1==slope2)
{
  printf("\n Three points fall on the same line");
}
  else
{
  printf("\nThree points doesn't fall on the same line");
}
  return (0);
}

 output:-
   Enter 1st co-ordinate (x1,y1) =(1,1)
   Enter 2nd co-ordinate (x2,y2) =(1,1)
   Enter 3rd co-ordinate (x3,y3) =(1,1)
   Three points fall on the same line