chap22.lst

Borland C++ Builder The Complete Reference 例程源代码

listing 1
#include <iostream> 
#include <cstdlib> 
#include <ctime> 
using namespace std; 
 
class timer{ 
  int seconds; 
public: 
  // seconds specified as a string 
  timer(char *t) { seconds = atoi(t); } 
 
  // seconds specified as integer 
  timer(int t) { seconds = t; } 
 
  // time specified in minutes and seconds 
  timer(int min, int sec) { seconds = min*60 + sec; } 
 
  void run(); 
} ; 
 
void timer::run() 
{ 
  clock_t t1, t2; 
 
  t1 = t2 = clock()/CLK_TCK; 
  while(seconds) { 
    if(t1/CLK_TCK+1 <= (t2=clock())/CLK_TCK) { 
       seconds--; 
       t1 = t2; 
    } 
  } 
  cout << "\a"; // ring the bell 
} 
 
int main() 
{ 
  timer a(10), b("20"), c(1, 10); 
 
  a.run(); // count 10 seconds 
  b.run(); // count 20 seconds 
  c.run(); // count 1 minute, 10 seconds 
 
  return 0; 
}

listing 2
/* Incorrect in C */ 
void f() 
{ 
  int i; 
  i = 10; 
  int j; 
  /* ... */ 
}

listing 3
#include <iostream> 
#include <cstring> 
using namespace std; 
 
int main() 
{ 
  int i; 
  i = 10; 
 
  int j = 100; // perfectly legal in C++ 
 
  cout << i*j << "\n"; 
  cout << "Enter a string: "; 
  char str[80];  // also legal in C++ 
  cin >> str; 
 
  // display the string in reverse order 
  int k;  // in C++, declare k where it is needed 
  k = strlen(str); 
  k--; 
  while(k>=0) { 
    cout << str[k]; 
    k--; 
  } 
 
  return 0; 
}

listing 4
#include <iostream> 
#include <cstdlib> 
#include <ctime> 
using namespace std; 
 
class timer{ 
  int seconds; 
public: 
  // seconds specified as a string 
  timer(char *t) { seconds = atoi(t); } 
 
  // seconds specified as integer 
  timer(int t) { seconds = t; } 
 
  // time specified in minutes and seconds 
  timer(int min, int sec) { seconds = min*60 + sec; } 
 
  void run(); 
} ; 
 
void timer::run() 
{ 
  clock_t t1, t2; 
 
  t1 = t2 = clock()/CLK_TCK; 
  while(seconds) { 
    if(t1/CLK_TCK+1 <= (t2=clock())/CLK_TCK) { 
       seconds--; 
       t1 = t2; 
    } 
  } 
  cout << "\a"; // ring the bell 
} 
int main() 
{ 
  timer a(10);  
  a.run(); 
 
  cout << "Enter number of seconds: "; 
  char str[80]; 
  cin >> str; 
  timer b(str); // initialize at runtime using a string 
  b.run(); 
 
  cout << "Enter minutes and seconds: "; 
  int min, sec; 
  cin >> min >> sec; 
  timer c(min, sec);  /* initialize at runtime 
                         using minutes and seconds */ 
  c.run(); 
 
  return 0; 
}

listing 5
#include <iostream> 
using namespace std; 
 
float myfunc(float i); 
double myfunc(double i); 
 
int main() 
{ 
  cout << myfunc(10.1) << " "; // unambiguous, calls myfunc(double) 
  cout << myfunc(10);  // ambiguous 
 
  return 0; 
} 
 
float myfunc(float i) 
{ 
  return i; 
} 
 
double myfunc(double i) 
{ 
  return -i; 
}

listing 6
#include <iostream> 
using namespace std; 
 
char myfunc(unsigned char ch); 
char myfunc(char ch); 
 
int main() 
{ 
  cout << myfunc('c');  // this calls myfunc(char) 
  cout << myfunc(88) << " "; // ambiguous 
 
  return 0; 
} 
 
char myfunc(unsigned char ch) 
{ 
  return ch-1; 
} 
 
char myfunc(char ch) 
{ 
  return ch+1; 
}

listing 7
#include <iostream> 
using namespace std; 
 
int myfunc(int i); 
int myfunc(int i, int j=1); 
 
int main() 
{ 
  cout << myfunc(4, 5) << " ";  // unambiguous 
  cout << myfunc(10);  // ambiguous 
 
  return 0; 
} 
 
int myfunc(int i) 
{ 
  return i; 
} 
 
int myfunc(int i, int j) 
{ 
  return i*j; 
}

listing 8
#include <iostream> 
using namespace std; 
 
int myfunc(int a); 
int myfunc(int a, int b); 
 
int main() 
{ 
  int (*fp)(int a);  // pointer to int xxx(int) 
 
  fp = myfunc;  // points to myfunc(int) 
  cout << fp(5); 
 
  return 0; 
} 
 
int myfunc(int a) 
{ 
  return a; 
} 
 
int myfunc(int a, int b) 
{ 
  return a*b; 
}

listing 9
#include <iostream> 
using namespace std; 
 
class cl { 
  int i; 
public: 
  void load_i(int val) { this->i = val; } // same as i = val 
  int get_i() { return this->i; } // same as return i 
} ; 
 
int main() 
{ 
  cl o; 
 
  o.load_i(100); 
  cout << o.get_i(); 
 
  return 0; 
}

listing 10
#include <iostream> 
using namespace std; 
 
class three_d { 
  int x, y, z; // 3-d coordinates 
public: 
  three_d operator+(three_d t); 
  three_d operator=(three_d t); 
 
  void show() ; 
  void assign(int mx, int my, int mz); 
} ; 
 
// Overload the +. 
three_d three_d::operator+(three_d t) 
{ 
  three_d temp; 
 
  temp.x = x+t.x; 
  temp.y = y+t.y; 
  temp.z = z+t.z; 
  return temp; 
} 
 
// Overload the =. 
three_d three_d::operator=(three_d t) 
{ 
  x = t.x; 
  y = t.y; 
  z = t.z; 
  return *this; 
} 
 
// Show X, Y, Z coordinates. 
void three_d::show() 
{ 
  cout << x << ", "; 
  cout << y << ", "; 
  cout << z << "\n"; 
} 
 
// Assign coordinates. 
void three_d::assign(int mx, int my, int mz) 
{ 
  x = mx; 
  y = my; 
  z = mz; 
} 
 
int main() 
{ 
  three_d a, b, c; 
 
  a.assign(1, 2, 3); 
  b.assign(10, 10, 10); 
 
  a.show(); 
  b.show(); 
 
  c = a+b;  // now add a and b together 
  c.show(); 
 
  c = a+b+c; // add a, b and c together 
  c.show(); 
 
  c = b = a;  // demonstrate multiple assignment 
  c.show(); 
  b.show(); 
 
  return 0; 
}

listing 11
#include <iostream> 
using namespace std; 
 
class three_d { 
  int x, y, z; // 3-d coordinates 
public: 
  three_d operator+(three_d op2);  // op1 is implied 
  three_d operator=(three_d op2);  // op1 is implied 
  three_d operator++(); // op1 is also implied here 
 
  void show() ; 
  void assign(int mx, int my, int mz); 
} ; 
 
// Overload the +. 
three_d three_d::operator+(three_d op2) 
{ 
  three_d temp; 
 
  temp.x = x+op2.x;  // these are integer additions 
  temp.y = y+op2.y;  // and the + retains its original 
  temp.z = z+op2.z;  // meaning relative to them 
  return temp; 
} 
 
// Overload the =. 
three_d three_d::operator=(three_d op2) 
{ 
  x = op2.x; // these are integer assigments 
  y = op2.y; // and the = retains its original 
  z = op2.z; // meaning relative to them 
  return *this; 
} 
 
// Overload a unary operator. 
three_d three_d::operator++() 
{ 
  x++; 
  y++; 
  z++; 
  return *this; 
} 
 
// Show X, Y, Z coordinates. 
void three_d::show() 
{ 
  cout << x << ", "; 
  cout << y << ", "; 
  cout << z << "\n"; 
} 
 
// Assign coordinates. 
void three_d::assign(int mx, int my, int mz) 
{ 
  x = mx; 
  y = my; 
  z = mz; 
} 
 
int main() 
{ 
  three_d a, b, c; 
 
  a.assign(1, 2, 3); 
  b.assign(10, 10, 10); 
 
  a.show(); 
  b.show(); 
 
  c = a+b;  // now add a and b together 
  c.show(); 
 
  c = a+b+c; // add a, b and c together 
  c.show(); 
 
  c = b = a;  // demonstrate multiple assignment 
  c.show(); 
  b.show(); 
 
  ++c;  // increment c 
  c.show(); 
  return 0; 
}

listing 12
loc operator++(int x);

listing 13
#include <iostream> 
using namespace std; 
 
class three_d { 
  int x, y, z; // 3-d coordinates 
public: 
  friend three_d operator+(three_d op1, three_d op2); 
  three_d operator=(three_d op2);  // op1 is implied 
  three_d operator++(); // op1 is implied here, too 
 
  void show() ; 
  void assign(int mx, int my, int mz); 
} ; 
 
// This is now a friend function. 
three_d operator+(three_d op1, three_d op2) 
{ 
  three_d temp; 
 
  temp.x = op1.x + op2.x;  // these are integer additions 
  temp.y = op1.y + op2.y;  // and the + retains its original 
  temp.z = op1.z + op2.z;  // meaning relative to them 
  return temp; 
} 
 
// Overload the =. 
three_d three_d::operator=(three_d op2) 
{ 
  x = op2.x; // these are integer assignments 
  y = op2.y; // and the = retains its original 
  z = op2.z; // meaning relative to them 
  return *this; 
} 
 
// Overload a unary operator. 
three_d three_d::operator++() 
{ 
  x++; 
  y++; 
  z++; 
  return *this; 
} 
 
// Show X, Y, Z coordinates. 
void three_d::show() 
{ 
  cout << x << ", "; 
  cout << y << ", "; 
  cout << z << "\n"; 
} 
 
// Assign coordinates. 
void three_d::assign(int mx, int my, int mz) 
{ 
  x = mx; 
  y = my; 
  z = mz; 
} 
int main() 
{ 
  three_d a, b, c; 
 
  a.assign(1, 2, 3); 
  b.assign(10, 10, 10); 
 
  a.show(); 
  b.show(); 
 
  c = a+b;  // now add a and b together 
  c.show(); 
 
  c = a+b+c; // add a, b and c together 
  c.show(); 
 
  c = b = a;  // demonstrate multiple assignment 
  c.show(); 
  b.show(); 
 
  ++c;  // increment c 
  c.show(); 
 
  return 0; 
}

listing 14
#include <iostream> 
using namespace std; 
 
class CL { 
public: 
  int count; 
  CL operator=(int i); 
  friend CL operator+(CL ob, int i); 
  friend CL operator+(int i, CL ob); 
}; 
 
CL CL::operator=(int i) 
{ 
  count = i; 
  return *this; 
} 
 
// This handles ob + int. 
CL operator+(CL ob, int i) 
{ 
  CL temp; 
 
  temp.count = ob.count + i; 
  return temp;