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Jim Blumberg posted
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I would suggest that you look at the documentation for printf(), pay particular attention to the width and precision modifiers.
This link may explain the width and precision modifiers a little better.
Jim
This link may explain the width and precision modifiers a little better.
Jim
regarding formatting numbers.
I have a similar question re: floating point numbers, the questions are in the comments of the code. I would be interested in how other beginners would attack the problem as well, sharing ideas and all that stuff.
Bear with my programming style, I am trying something newsince I started reading Practical C++ Programming from O'Reilly, awesome book with many insights into programming in general.
On with the code.
/*************************************************************************/
/* sphere.cpp: -- program to calculate the volume of a sphere */
/* */
/* Author: -- Bryston */
/* */
/* PURPOSE: -- Practical C++ exercise 5-2 */
/* */
/* USAGE: -- user enters a number */
/* */
/*************************************************************************/
#include<iostream>// for all the i/o goodness
#include<iomanip>
using namespace std;// so we don't have to use verbose std::cin etc...
// Global Variables
const long double PI=3.1415926; // declare PI as a constant
long double sphere_radius=0.0; //radius of the sphere from the user
long double sphere_volume=0.0; //volume of the sphere
long double r_cubed=0.0; //the value of the radius cubed
/**************************************************************************
******************************** WARNING **********************************
******************* IF YOU STEAL THIS CODE AND SUBMIT IT ******************
***************** AS YOUR HOMEWORK YOU MAY FAIL YOUR COURSE****************
*********** AND END UP FLIPPING BURGERS FOR THE REST OF YOUR LIFE**********
***************************************************************************
**************************************************************************/
int main(){
//>>>>>>>>>>>>>>>>>>>>> Initial Display Section <<<<<<<<<<<<<<<<<<<<<<<<<<<
while (1){
cout << endl << "Calculate the volume of a sphere!";
cout << endl << "The user supplies the radius of the sphere.";
cout << endl << "Will display the results of ((4/3)*PI)*r^3";
cout << endl << endl << "Please enter the value for r (0 to exit):> ";
//>>>>>>>>>>>>>>>>>>>>> Get User Input Section <<<<<<<<<<<<<<<<<<<<<<<<<<<<
cin >> sphere_radius;// user supplied floating point value
if (sphere_radius == 0)// give the user a way to exit the program
break;// exit the while loop
//>>>>>>>>>>>>>>>>>>>>> Process Data Section <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
/* Calculate volume of a sphere from known radius supplied by the user.
Using the variable r_cubed to make the actual formula flow a little
better. Could have done it by including the cmath header file
and using pow(r,3) */
r_cubed = sphere_radius * sphere_radius * sphere_radius;
// remember to use the decimal point for type float or double!!!
sphere_volume = ((4.0 / 3.0) * (PI * r_cubed));
//>>>>>>>>>>>>>>>>>>>>> Display Results Section <<<<<<<<<<<<<<<<<<<<<<<<<<<
/************************ UNEXPECTED RESULTS *****************************/
// any input that yields a result higher than 99999.9 (approx 28.75)
// will cause the decimal point to go POOFng
// compiled it in DevC++ and Visual C++2010 with equal results
// using setprecision(n) from <iomanip> gives a better result
// but doesn't scale well to a wide range of inputs
// too precise for small inputs && not precise enough for large inputs
// input of 2880 once again strips the decimal if setprecision(12)
// is there a way to use setprecision or something else to force
// a result that is always exactly (n) digits after the decimal point?
cout << endl << endl << "A sphere with the radius : " << sphere_radius;
cout << " units" << endl << "has a volume of ";
// setprecision(n) inline helps preserve the decimal up to a point
cout << setprecision(12) << sphere_volume << " cubic units.";
cout << endl << endl;
}// end while loop
return (0);
}// end function main
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