Управляващи оператори - II

do
{ statements
}
while (condition);

do
{  xold = xnew;
   xnew = (xold + a / xold) / 2;
}
while (fabs(xnew - xold) > EPSILON);
// sqroot.cpp
#include <iostream>
#include <cmath>
using namespace std;

int main()
{  cout << "Please enter a number: ";
   double a;
   cin >> a;
   
   const double EPSILON = 1E-14;
   double xnew = a;
   double xold;

   do
   {  xold = xnew;
      xnew = (xold + a / xold) / 2;
   }
   while (fabs(xnew - xold) > EPSILON);

   cout << "The square root is " << xnew << "\n";
   return 0;
}

print table header
double rate;
for (rate = RATE_MIN; rate <= RATE_MAX;
     rate = rate + RATE_INCR)
{  print table row
}

cout << "Rate     ";
int year;
for (year = YEAR_MIN; year <= YEAR_MAX;
     year = year + YEAR_INCR)
{  cout << setw(2) << year << " years";
}

// table.cpp
#include <iostream>
#include <iomanip>
#include <cmath>

using namespace std;

int main()
{  const double RATE_MIN = 5;
   const double RATE_MAX = 10;
   const double RATE_INCR = 0.5;
   const int YEAR_MIN = 5;
   const int YEAR_MAX = 30;
   const int YEAR_INCR = 5;

   /* print table header */

   cout << " Rate  ";
   int year;
   for (year = YEAR_MIN; year <= YEAR_MAX; 
        year = year + YEAR_INCR)
      cout << setw(2) << year << " years  ";

   cout << "\n";
   cout << fixed << setprecision(2);

   double rate;
   double initial_balance = 10000;
   for (rate = RATE_MIN; rate <= RATE_MAX; 
        rate = rate + RATE_INCR)
   {  
      /* print table row */
       int year;
       cout << setw(5) << rate;
       for (year = YEAR_MIN; year <= YEAR_MAX;
          year = year + YEAR_INCR)
       {  double balance = 
             initial_balance * pow(1 + rate/100, year);
          cout << setw(10) << balance;
       }
       cout << "\n";
   }
   return 0;
}

// words.cpp
#include <iostream>
#include <string>
using namespace std;

int main()
{  int count = 0;
   string word;
   while (cin >> word) count++;

   cout << count << " words." << endl;
   return 0;
}

string line;
while (getline(cin, line))
{  process line
}

char ch;
while (cin.get(ch))
{  process ch
}

int main()
{  int i;
   for (i = 1; i <= 10; i++)
   {  
	int r = rand();
      	cout << r << "\n";
   }
   return 0;
}

int rand_int(int a, int b)
{  
	return a + rand() % (b - a + 1);
}

// dice.cpp 
#include <iostream>
#include <string>
#include <cstdlib>
#include <ctime>
using namespace std;

/**
   Sets the seed of the random number generator.
*/
void rand_seed()
{  int seed = static_cast<int>(time(0));
   srand(seed);
}
/** 
   Compute a random integer in a range
   @param a the bottom of the range
   @param b the top of the range
   @return a random integer x, a <= x and x <= b
*/
int rand_int(int a, int b)
{  return a + rand() % (b - a + 1);
}

int main()
{  rand_seed();
   int i;
   for (i = 1; i <= 10; i++)
   {  int d1 = rand_int(1, 6);
      int d2 = rand_int(1, 6);
      cout << d1 << " " << d2 << "\n";
   }
   cout << "\n";
   return 0;
}

double rand_double(double a, double b)
{  
	return a + (b - a) * rand() * (1.0 / RAND_MAX);
}

void rand_seed() 
/* ЦЕЛ: Инициализира генератора за случайни числа 
*/ 
{  int seed = static_cast<int>(time(0)); 
   srand(seed); 
} 
double rand_double(double a, double b) 
/* ЦЕЛ:  намира случайно число в интервала [a, b] 
   ПОЛУЧАВА: границите на интервала 
   ВРЪЩА: случайно число x, a <= x и x <= b 
*/ 
{  return a + (b - a)*rand()*(1.0/RAND_MAX); 
} 
double deg2rad(double alpha) 
/* ЦЕЛ:  превръща градуси в радиани 
   ПОЛУЧАВА: alpha - големина на ъгъл в градуси 
   ВРЪЩА:  големината на ъгъла в радиани 
*/ 
{  const double PI = 3.141592653589793; 
   return alpha * PI / 180; 
} 
int main() 
{  int NTRIES = 10000; 
   int i; 
   int hits = 0; 
   rand_seed(); 
   for (i = 1; i <= NTRIES; i++) 
   {  double ylow = rand_double(0, 2); 
      double angle = rand_double(0, 180); 
      double yhigh = ylow + sin(deg2rad(angle)); 
      if (yhigh >= 2) hits++; 
   } 
   cout << "Tries / Hits = " << NTRIES*(1.0/hits) << "\n"; 
   return 0; 
}