Equation of straight line passing through two points

Problem Statement
Write a c code to print the equation of straight line joining two given cartesian points X(x1,y1) and Y(x2,y2).
the formet of the equation is y=mx+c

#include<stdio.h> #define to .5 int main() { float x1,x2,y1,y2,m,c; printf("enter the value of x1 and y1 \n"); scanf("%f %f",&x1,&y1); printf("enter the value of x2 and y2 \n"); scanf("%f %f",&x2,&y2); if(x1==x2&&y1==y2) { printf("they are same points infinite number of lines are possible\n"); } else if(x1==x2||y1==y2) { if(x1==x2) printf("the equation of line is x= %f",x1); else printf("the equation of line is y= %f",y1); } else { m= (y2-y1)/(x2-x1); c=y2-(m*x2); printf("the equation of line is y=%fx+%f \n",m,c); } return 0; }