#include <stream.hxx>#include <string.h> extern void exit(int);class string { struct srep { char* s; int n; }; srep *p; public: string(char *); string(); string(string &); string& operator=(char *); string& operator=(string &); ~string(); char& operator[](int i); friend ostream& operator<<(ostream&, string&); friend istream& operator>> (istream&, string&); 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; } 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];}
