#include <stdio.h>
#include <stdarg.h>

static const double pi = 3.14159265358979;

void heading(const char *text)
{
   printf("\n%s\n________\n\n", text);
}

void prompt(unsigned int count, ...)
{
   unsigned int i;

   va_list va;
   va_start(va, count);

   for (i = 0; i < count; i++)
   {
      printf("Please enter %s : ", va_arg(char*));
      scanf("%f", va_arg(float*));
      printf("\n");
   }

   va_end(va);
}

void tail(void)
{
   puts("**********************************************************");
   fflush(stdin);
}

main()
{
   puts("     >>>>This program calculates many geometrical formulas<<<<");

   {
      float     length;
      float     width;
      float     peri;

      heading("Perimeter of Square and Rectangle");

      prompt(2, "the length of side a", &length,
                "the length of side b", &width);

      peri = 2 * (length + width);

      printf("The perimeter of the square/rectangle is %.2f units squared\n", peri);

      tail();
   }

   {
      float     lengthl;
      float     widthw;
      float     arealw;

      heading("Area of Square and Rectangle");

      prompt(2, "the length of side a", &lengthl,
                "the length of side b", &widthl);

      arealw = lengthl * widthw;
      printf("The area of the square/rectangle is %.3f units squared\n", arealw);

      tail();
   }

   {
      float     sidea;
      float     sideb;
      float     sidec;
      float     perimeter;

      heading("Perimeter of Triangle");

      prompt(3, "the length of side a", &sidea,
                "the length of side b", &sideb,
                "the length of side c", &sidec);

      perimeter = sidea + sideb + sidec;
      printf("The perimeter of the triangle is : %.2f units\n", perimeter);

      tail();
   }

   {
      float     base;
      float     height;
      float     area;

      heading("Area of Triangle");

      prompt(2, "the length of the base", &base,
                "the length of the height", &height);

      area = .5 * (base * height);
      printf("The area of the triangle is %.2f units squared\n", area);

      tail();
   }

   {
      float     areabase;
      float     perimeterbase;
      float     side3len;
      float     surareat;

      heading("Triangular Prism");

      prompt(3, "the perimeter of base", &perimeterbase,
                "the area of base", &areabase,
                "the length of side h", &side3len);

      surareat = 2 * areabase + perimeterbase * side3len;
      printf("The surface area of the triangular prism is : %.3f units squared\n",surareat);

      tail();
   }

   {
      float     s1;
      float     s2;
      float     s3;
      double    surarea;

      heading("Rectangular Prism");

      prompt(3, "the length of s1", &s1,
                "the length of s2", &s2,
                "the length of s3", &s3);

      surarea = 2 * s1 * s2 + 2 * s2 * s3 + 2 * s1 * s3;

      printf("The surface area of the rectangular prism is : %.4f units squared\n", surarea);

      tail();
   }

   {
      float     s1c;
      float     surareac;

      heading("Cube");

      prompt(1, "the length of one side", &s1c);

      surareac = 6 * s1c *s1c;
      printf("The surface area of the cube is : %.3f units squared\n", surareac);

      tail();
   }

   {
      float     sphererad;
      double    spherearea;

      heading("Sphere");

      prompt(1, "the radius of the sphere", &sphererad);

      printf("\n");

      spherearea = 4 * pi * sphererad * sphererad;
      printf("The surface area of the sphere is %.4f units squared\n", spherearea);

      tail();
   }

   getchar();
}