C Program to implement Simpson's 1/3 rd Rule

/*

 Simpson's 1/3 Rule
 Equation: x/(1+x) dx
 lower limit=0 upper limit=1 number of interval=6
*/
#include<conio.h>
#include<stdio.h>
void main()
{
 float a,b,h,x,y,so=0;
 float x0,y0,yn,xn,r,se=0;;
 int i,n;
 float f(float);
 clrscr();
 printf("\nEnter lower limit value:: ");
 scanf("%f",&a);
 printf("\nEnter upper limit value:: ");
 scanf("%f",&b);
 printf("\nEnter the number of intervals:: ");
 scanf("%d",&n);
 h=(b-a)/n;
 x0=a;
 y0=f(x0);
 yn=f(b);
 x=x0+h;
 for(i=1;i<=n-1;i=i+2)
 {
  y=f(x);
  so=so+y;
  x=x+2*h;
 }
 x=x0+2*h;
 for(i=2;i<=n-2;i=i+2)
 {
  y=f(x);
  se=se+y;
  x=x+2*h;
 }
 r=(h/3)*(y0+yn+4*so+2*se);
 printf("\nResult is:: %f",r);
 getch();
}
float f(float x)
{
 return x/(1+x);
}