chap8.lst

The Art of C++一书的配套源代码

listing 1
#include <iostream> 
#include <cmath> 
#include <iomanip> 
#include <locale> 
 
using namespace std; 
 
// Compute ;the regular payments on a loan. 
double regpay(double principal, double intRate, 
              int numYears, int payPerYear) {  
  double numer;  
  double denom;  
  double b, e;  
  
  intRate /= 100.0; // convert percentage to fraction  
 
  numer = intRate * principal / payPerYear;  
 
  e = -(payPerYear * numYears);  
  b = (intRate / payPerYear) + 1.0;  
  
  denom = 1.0 - pow(b, e);  
  
  return numer / denom;  
}    
 
int main() { 
  double p, r; 
  int y, ppy; 
 
  // Set locale to English.  Adjust as necessary 
  // for your language and/or egion. 
  cout.imbue(locale("english")); 
 
  cout << "Enter principal: "; 
  cin >> p; 
 
  cout << "Enter interest rate (as a percentage): "; 
  cin >> r; 
 
  cout << "Enter number years: "; 
  cin >> y; 
 
  cout << "Enter number of payments per year: "; 
  cin >> ppy; 
 
  cout << "\nPayment: " << fixed << setprecision(2) 
       << regpay(p, r, y, ppy) << endl; 
 
  return 0; 
}

listing 2
#include <iostream> 
#include <cmath> 
#include <iomanip> 
#include <locale> 
 
using namespace std; 
   
// Compute the future value of an investment.  
double futval(double principal, double rateOfRet, 
              int numYears, int compPerYear) {  
  double b, e; 
  
  rateOfRet /= 100.0; // convert percentage to fraction  
 
  b = (1 + rateOfRet/compPerYear); 
  e = compPerYear * numYears; 
  
  return principal * pow(b, e); 
} 
 
int main() { 
  double p, r; 
  int y, cpy; 
 
  // Set locale to English.  Adjust as necessary 
  // for your language and/or egion. 
  cout.imbue(locale("english")); 
 
  cout << "Enter principal: "; 
  cin >> p; 
 
  cout << "Enter rate of return (as a percentage): "; 
  cin >> r; 
 
  cout << "Enter number years: "; 
  cin >> y; 
 
  cout << "Enter number of compoundings per year: "; 
  cin >> cpy; 
 
  cout << "\nFuture value: " << fixed << setprecision(2) 
       << futval(p, r, y, cpy) << endl; 
 
  return 0; 
}

listing 3
#include <iostream> 
#include <cmath> 
#include <iomanip> 
#include <locale> 
 
using namespace std; 
   
// Compute the initial investment necessary for  
// a specified future value. 
double initval(double targetValue, double rateOfRet, 
               int numYears, int compPerYear) {  
  double b, e;  
 
  rateOfRet /= 100.0; // convert percentage to fraction  
 
  b = (1 + rateOfRet/compPerYear);  
  e = compPerYear * numYears;  
  
  return targetValue / pow(b, e);    
}     
 
int main() { 
  double p, r; 
  int y, cpy; 
 
  // Set locale to English.  Adjust as necessary 
  // for your language and/or egion. 
  cout.imbue(locale("english")); 
 
  cout << "Enter desired future value: "; 
  cin >> p; 
 
  cout << "Enter rate of return: "; 
  cin >> r; 
 
  cout << "Enter number years: "; 
  cin >> y; 
 
  cout << "Enter number of compoundings per year: "; 
  cin >> cpy; 
 
  cout << "\nInitial investment required: "  
       << fixed << setprecision(2) 
       << initval(p, r, y, cpy) << endl; 
 
  return 0; 
}

listing 4
#include <iostream> 
#include <cmath> 
#include <iomanip> 
#include <locale> 
 
using namespace std; 
 
// Compute the initial investment necessary for  
// a desired annuity. In other words, it finds  
// the initial amount needed to allow the regular  
// withdrawls of a desired amount over a period  
// of time.  
double annuity(double regWD, double rateOfRet, 
               int numYears, int numPerYear) {  
 
  double b, e;  
  double t1, t2;  
  
  rateOfRet /= 100.0; // convert percentage to fraction  
 
  t1 = (regWD * numPerYear) / rateOfRet;  
  
  b = (1 + rateOfRet/numPerYear);  
  e = numPerYear * numYears;  
  
  t2 = 1 - (1 / pow(b, e));  
     
  return t1 * t2;  
} 
 
int main() { 
  double wd, r; 
  int y, wpy; 
 
  // Set locale to English.  Adjust as necessary 
  // for your language and/or egion. 
  cout.imbue(locale("english")); 
 
  cout << "Enter desired withdrawal: "; 
  cin >> wd; 
 
  cout << "Enter rate of return (as a percentage): "; 
  cin >> r; 
 
  cout << "Enter number years: "; 
  cin >> y; 
 
  cout << "Enter number of withdrawals per year: "; 
  cin >> wpy; 
 
  cout << "\nInitial investment required: "  
       << fixed << setprecision(2) 
       << annuity(wd, r, y, wpy) << endl; 
 
  return 0; 
}

listing 5
#include <iostream> 
#include <cmath> 
#include <iomanip> 
#include <locale> 
 
using namespace std; 
 
// Compute the maximum annuity that can  
// be withdrawn from an investment over  
// a period of time.  */  
double maxwd(double principal, double rateOfRet, 
             int numYears, int numPerYear) {  
 
  double b, e;  
  double t1, t2;  
  
  rateOfRet /= 100.0; // convert percentage to fraction  
 
  t1 = rateOfRet / numPerYear;  
  
  b = (1 + t1);  
  e = numPerYear * numYears;  
  
  t2 = pow(b, e) - 1;  
  
  return principal * (t1/t2 + t1);  
}     
 
int main() { 
  double p, r; 
  int y, wpy; 
 
  // Set locale to English.  Adjust as necessary 
  // for your language and/or egion. 
  cout.imbue(locale("english")); 
 
  cout << "Enter principal: "; 
  cin >> p; 
 
  cout << "Enter rate of return (as a percentage): "; 
  cin >> r; 
 
  cout << "Enter number years: "; 
  cin >> y; 
 
  cout << "Enter number of withdrawals per year: "; 
  cin >> wpy; 
 
  cout << "\nMaximum withdrawal: " << fixed << setprecision(2) 
       << maxwd(p, r, y, wpy) << endl; 
 
  return 0; 
}

listing 6
#include <iostream> 
#include <cmath> 
#include <iomanip> 
#include <locale> 
 
using namespace std; 
   
// Find the remaining balance on a loan.  
double balance(double principal, double intRate, 
               double payment, int payPerYear, 
               int numPayments) {  
 
  double bal = principal;  
  double rate = intRate / payPerYear;  
  
  rate /= 100.0; // convert percentage to fraction  
 
  for(int i = 0; i < numPayments; i++)  
    bal -= payment - (bal * rate);  
  
  return bal;  
} 
 
int main() { 
  double p, r, pmt; 
  int ppy, npmt; 
 
  // Set locale to English.  Adjust as necessary 
  // for your language and/or egion. 
  cout.imbue(locale("english")); 
 
  cout << "Enter original principal: "; 
  cin >> p; 
 
  cout << "Enter interest rate (as a percentage): "; 
  cin >> r; 
 
  cout << "Enter payment: "; 
  cin >> pmt; 
 
  cout << "Enter number of payments per year: "; 
  cin >> ppy; 
 
  cout << "Enter number of payments made: "; 
  cin >> npmt; 
 
  cout << "Remaining balance: " << fixed << setprecision(2) 
       << balance(p, r, pmt, ppy, npmt) << endl; 
 
  return 0; 
}