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Example 5

area2.cpp

    1   // File: area2.cpp
    2   // Description: Compute the area of some circles with radius 
    3   //              input by the user.
    4   // Author: 
    5   // Created: 07 Sep 05
    6   
    7   #include <iostream>
    8   
    9   using namespace std;
   10   
   11   int main()
   12   {
   13     const double pi = 3.1415926535897932384626433832795;
   14     double r;
   15     double a;
   16   
   17     cout << "\nThis program will calcuate the area of a circle" << endl;
   18     cout << "\nEnter a value for the radius of a circle: ";
   19     cin >> r;
   20   
   21     a = pi * r * r;
   22   
   23     cout.precision(3);
   24     cout.setf(ios::fixed);
   25     cout.setf(ios::showpoint);
   26   
   27     cout << "A circle of radius " << r << " has area " << a << endl;
   28   
   29     return 0;
   30   }
   31   
   32     

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