> 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];
>}
>#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);
>}
>#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";
>}
>#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",");
>}
