C++: Compute for the Volume (Rectangular, Cone, Cylinder etc)

#include <iostream> using namespace std;   int rectangular (int l, int w, int h) {   int rect_vol;   rect_vol=l*w*h;   return (rect_vol); } int prism (int a, int b) {   int pri_vol;   pri_vol=a*b;   return (pri_vol); } int cylinder (int a, int b) {   int cyl_vol,pi=3.1416;   cyl_vol=((pi)*(a*a)*b);   return (cyl_vol); } double pyramid (double a, double b) {   double pyr_vol;   pyr_vol=(a*b)/3;   return (pyr_vol); }  int cones (int a, int b) {   int con_vol,pi=3.1416;   con_vol=((pi)*((a*a)*b))/3;   return (con_vol); } double sphere (int a) {   int sph_vol,pi=3.1416;   sph_vol=(4/3)*((pi)*(a*a*a));   return (sph_vol); }
int main () {     char choice;   double l,w,h,r,b,pi=3.1416;   double rec,pri,cyl,pyr,con,sph;   cout<<"Choose a polygon: \na-Rectangular \nb-Prism\nc-Cylinder\nd-Pyramid\ne-Cones\nf-Sphere"<<endl;   cin>>choice;   switch (choice)   {   case 'a': cout<<"Enter length"; cin>>l; cout<<"Enter width"; cin>>w; cout<<"Enter height"; cin>>h; rec = rectangular (l,w,h); cout << "The volume of the rectangle is "<<rec; break; case 'b': cout<<"Enter base"; cin>>b; cout<<"Enter height"; cin>>h; pri = prism (b,h); cout << "The volume of the prism is "<<pri; break; case 'c': cout<<"Enter radius"; cin>>r; cout<<"Enter height"; cin>>h; cyl = cylinder (r,h); cout << "The volume of the cylinder is "<<cyl; break; case 'd': cout<<"Enter base"; cin>>b; cout<<"Enter height"; cin>>h; pyr = pyramid (b,h); cout << "The volume of the pyramid is "<<pyr; break; case 'e': cout<<"Enter radius"; cin>>r; cout<<"Enter height"; cin>>h; con = cones (r,h); cout << "The volume of the cones is "<<con; break; case 'f': cout<<"Enter radius"; cin>>r; sph = sphere (r); cout << "The volume of the sphere is "<<sph; break; default:  cout<<"Out of coverage"<<endl; }   return 0; }