Справочное руководство по C++ - [59]

 friend int operator!=(string&x, char *s)
  {return strcmp(x.p-›s, s) != 0;}

 friend int operator!=(string&x, string&y)
  {return strcmp (x.p-›s, y.p-›s) != 0;}
};

string::string()
{
 p = new srep;
 p-›s = 0;
 p-›n = 1;
}

string::string(char* s)
{
 p = new srep;
 p-›s = new char[strlen(s) +1];
 strcpy(p-›s, s);
 p-›n = 1;
}
string::string(string& x)
{
 x.p-›n++;
 p = x.p;
}

string::~string()
{
 if (--p-›n - 0) {
  delete p-›s;
  delete p;
 }
}

string& string::operator=(char* s)
{
 if (p-›n › 1) {
  p-›n--;
  p = new srep;
 }
 else if (p-›n == 1)
  delete p-›s;

 p-›s = new char[strlen(s)+1];
 strcpy(p-›s, s);
 p-›n = 1;
 return *this;
}

string& string::operator=(string& x)
{
 x.p-›n++;
 if (--p-›n == 0) {
  delete p-›s;
  delete p;
 }
 p = x.p;
 return *this;
}

ostream& operator‹‹(ostream& s, string& x)
{
 return s ‹‹ x.p-›s ‹‹ " [" ‹‹ x.p-›n ‹‹ "]\n";
}

istream& operator››(istream& s, string& x)
{
 char buf[256];
 s››buf;
 x = buf;
 cout ‹‹ "echo: " ‹‹ x ‹‹ "\n";
 return s;
}

void error(char* p)
{
 cout ‹‹ p ‹‹ "\n";
 exit(1);
}
char& string::operator[](int i)
{
 if (i‹0 || strlen(p-›s)‹i) error("index out of range");
 return p-›s[i];
}

main()
{
 string x[100];
 int n;

 cout ‹‹ "here we go\n";
 for (n = 0; cin››x[n]; n++) {
  string y;
  if (n==100) error("too many strings");
  cout ‹‹ (y = x[n]);
  if (y=="done") break;
 }
 cout ‹‹ "here we go back again\n";
 for (int i=n-1; 0‹=i; i--) cout ‹‹ x[i];
}

b7_2_8.cxx

#include ‹stream.hxx›

struct employee {
 friend class manager;
 employee* next;
 char* name;
 short department;
 virtual void print();
};

struct manager: employee {
 employee* group;
 short level;
 void print();
};

void employee::print()
{
 cout ‹‹ name ‹‹ "\t" ‹‹ department ‹‹ "\n";
}

void manager::print()
{
 employee::print();
 cout ‹‹ "\tlevel " ‹‹ level ‹‹ "\n";
}

void f(employee* ll)
{
 for (; ll; ll=ll-›next) ll-›print();
}

main ()
{
 employee e;
 e.name = "J. Brown";
 e.department = 1234;
 e.next = 0;
 manager m;
 m.name = "J. Smith";
 m.department = 1234;
 m.level = 2;
 m.next = &e;
 f(&m);
}

b7_7.cxx

#include ‹stream.hxx›

struct base { base(); };

struct derived: base { derived(); };

base:: base()
{
 cout ‹‹ "\tbase 1: this=" ‹‹ long(this) ‹‹ "\n";
 if (this == 0) this = (base*)27;
 cout ‹‹ "\tbase 2: this=" ‹‹ long(this) ‹‹ "\n";
}

derived::derived()
{
 cout ‹‹ "\tderived 1: this=" ‹‹ long(this) ‹‹ "\n";
 if (this == 0) this = (derived*)43;
 cout ‹‹ "\tderived 2: this=" ‹‹ long(this) ‹‹ "\n";
}

main()
{
 cout ‹‹ "base b;\n";
 base b;
 cout ‹‹ "new base;\n";
 new base;
 cout ‹‹ "derived d;\n";
 derived d;
 cout ‹‹ "new derived;\n";
 new derived;
 cout ‹‹ "new derived;\n";
 new derived;
 cout ‹‹ "at the end\n";
}

b8_3_3.cxx

#include ‹xstream.hxx›

extern void exit(int);

void error(char* s, char* s2)
{
 cerr ‹‹ s ‹‹ " " ‹‹ s2 ‹‹ "\n";
 exit(1);
}

main(int argc, char* argv[])
{
 if (argc != 3) error ("wrong number of arguments",");

 filebuf f1;
 if (f1.open(argv[1],input) == 0)
  error("cannot open input file",argv[1]);
 istream from(&f1);

 filebuf f2;
 if (f2.open(argv[2],output) == 0)
  error("cannot open input file",argv[2]);
 ostream to(&f2);

 char ch;
 while (from.get(ch)) to.put(ch);

 if (!from.eof() || to.bad())
  error("something strange happened",");
}