Справочное руководство по C++ — страница 40 из 41

}

main()
{
 const MAX = 256;
 char buf[MAX];
 assoc vec(512);
 while (cin››buf) vec[buf]++;
 vec.print_all();
}

b6_8.cxx

#include ‹stream.hxx›
#include ‹string.h›

struct pair {
 char* name;
 int val;
};

class assoc {
 friend class assoc_iterator;
 pair* vec;
 int max;
 int free;
public:
 assoc(int);
 int& operator[](char*);
};
class assoc_iterator {
 assoc* cs;
 int i;
public:
 assoc_iterator(assoc& s) { cs =&s; i = 0; }
 pair* operator()()
 { return (i‹cs-›free) ? &cs-›vec[i++] : 0; }
};

assoc::assoc(int s)
{
 max = (s‹16) ? s : 16;
 free = 0;
 vec = new pair[max];
}

int& assoc::operator[](char* p)
{
 register pair* pp;

 for (pp = &vec[free-1]; vec‹=pp; pp--)
  if (strcmp(p,pp-›name)==0) return pp-›val;

 if (free == max) {
  pair* nvec = new pair[max*2];
  for (int i=0; i‹max; i++) nvec[i] = vec[i];
  delete vec;
  vec = nvec;
  max = 2*max;
 }

 pp =&vec[free++];
 pp-›name = new char[strlen(p)+1];
 strcpy(pp-›name,p);
 pp-›val = 0;
 return pp-›val;
}

main()
{
 const MAX = 256;
 char buf[MAX];
 assoc vec(512);
 while (cin››buf) vec[buf]++;
 assoc_iterator next(vec);
 pair* p;
 while (p = next())
  cout ‹‹ p-›name ‹‹ ": " ‹‹ p-›val ‹‹ "\n";
}

b6_9.cxx

#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";