Бьярн Страустрап - Справочное руководство по C++

• Название: Справочное руководство по C++
• Автор: Бьярн Страустрап
• Жанр: Программирование

---

 int size() { return sz; }

 void set_size(int);

 int& operator[](int);

 int& elem(int i) { return v[i]; }

};

vector::vector(int s)

{

 if (s‹=0) error("bad vector size");

 sz = s;

 v = new int[s];

}

int& vector::operator[](int i)

{

 if (i‹0 || sz‹=i) error("vector index out of range");

 return v[i];

}

vector::~vector()

{

 delete v;

}

// 1.14

class Vec: public vector {

public:

 Vec(int s): (s) {}

 Vec(Vec&);

 ~Vec() {}

 void operator=(Vec&);

 void operator*=(Vec&);

 void operator*=(int);

};

Vec::Vec(Vec& a): (a.size())

{

 int sz = a.size();

 for (int i = 0; i‹sz; i++) elem(i) =a.elem(i);

}

void Vec::operator=(Vec& a)

{

 int s = size();

 if (s != a.size()) error("bad vector size for =");

 for (int i =0; i‹s; i++) elem(i)=a.elem(i);

}

Vec operator+(Vec& a, Vec& b)

{

 int s = a.size();

 if (s!= b.size()) error("bad vector size for +");

 Vec sum(s);

 for (int i=0; i‹s; i++)

 sum.elem(i) = a.elem(i) + b.elem(i);

 return sum;

}

void error(char* p)

{

 cerr ‹‹ p ‹‹ "\n";

 exit (1);

}

void vector::set_size(int) {}

main()

{

 Vec a(10);

 Vec b(10);

 for (int i=0; i‹a.size(); i++) a[i] = i;

 b = a;

 Vec c = a+b;

 for (i=0; i‹c.size(); i++) cout ‹‹ c[i] ‹‹ "\n";

}

b1__16.cxx

#include ‹vector.hxx›

declare(vector,int);

implement(vector,int);

main()

{

 vector(int) vv(10);

 vv[2] = 3;

 vv[10] = 4; // range error

}

b2_1_3.cxx

#include ‹stream.hxx›

int a = 1;

void f()

{

 int b = 1;

 static int c = 1;

 cout ‹‹ " a = " ‹‹ a++

  ‹‹ " b = " ‹‹ b++

  ‹‹ " c = " ‹‹ c++ ‹‹ "\n";

}

main ()

{

 while (a ‹ 4) f();

}

b2_3.cxx

#include ‹stream.hxx›

main()

{

 int* p = new int;

 cout ‹‹ "sizeof(int) = " ‹‹ sizeof(int) "\n";

}

b2_3_6a.cxx

#include ‹stream.hxx›

extern int strlen(char*);

char alpha[] = "abcdefghijklmnopqrstuvwxyz";

main ()

{

 int sz = strlen(alpha);

for (int i=0; i‹sz; i++) {

 char ch = alpha[i];

 cout ‹‹ "'" ‹‹ chr(ch) ‹‹ "'"

  ‹‹ " = " ‹‹ ch

  ‹‹ " = 0" ‹‹ oct(ch)

  ‹‹ " = 0x" ‹‹ hex(ch) ‹‹ "\n";

 }

}

b2_3_6b.cxx

#include ‹stream.hxx›

char v[2][5] = {

 'a', 'b', 'c', 'd', 'e',

 '0', '1', '2', '3', '4'

};

main() {

 for (int i = 0; i‹2; i++) {

  for (int j = 0; j ‹5; j++)

   cout ‹‹ "v[" ‹‹ i ‹‹ "][" ‹‹ j

    ‹‹ "]=" ‹‹ chr(v[i][j]) ‹‹ " ";

  cout ‹‹ "\n";

 }

}

b2_3_7.cxx

#include ‹stream.hxx›

main()

{

 char cv[10];

 int iv[10];

 char* pc = cv;

 int* pi = iv;

 cout ‹‹ "char* " ‹‹ long(pc+1)-long(pc) ‹‹ "\n";

 cout ‹‹ "int* " ‹‹ long(pi+1)-long(pi) ‹‹ "\n";

}

b2_3__10.cxx

#include ‹stream.hxx›

struct pair {

 char* name;

 int val;

};

extern int strlen(char*);

extern int strcpy(char*, char*);

extern int strcmp(char*, char*);

const large = 1024;

static pair vec[large];

pair* find(char* p)

{

 for (int i=0; vec[i].name; i++)

  if (strcmp(p,vec[i].name)==0) return &vec[i];

 if (i == large) return &vec[large-1];

 return &vec[i];

}

int& value(char* p)

{

 pair* res = find(p);

 if (res-›name == 0) {

  res-›name = new char[strlen(p)+1];

  strcpy(res-›name,p);

  res-›val = 0;

 }

 return res-›val;

}

const MAX = 256;

main ()

{

 char buf [MAX];

 while (cin››buf) value(buf)++;

 for (int i=0; vec[i].name; i++)

  cout ‹‹ vec[i].name ‹‹ ":" ‹‹ vec[i].val ‹‹ "\n";

}

b3_1all.cxx

#include ‹xstream.hxx›

#include ‹ctype.h›

enum token_value {

 NAME, NUMBER, END,

 PLUS = '+', MINUS = '-', MUL='*', DIV='/',

 PRINT=';', ASSIGN='=', LP='(', RP=')'

};

token_value curr_tok;

struct name {

 char* string;

 name* next;

 double value;

};

const TBLSZ = 23;

name* table[TBLSZ];

int no_of_errors;

double error(char* s) {

 cerr ‹‹ "error: " ‹‹ s ‹‹ "\n";

 no_of_errors++;

 return 1;

}

extern int strlen(const char*);

extern int strcmp(const char*, const char*);

extern char* strcpy(char*, const char*);

name* look(char* p, int ins = 0)

{

 int ii= 0;

 char *pp = p;

 while (*pp) ii = ii‹‹1 ^ *pp++;

 if (ii ‹ 0) ii = -ii;

 ii %= TBLSZ;

 for (name* n=table [ii]; n; n=n-›next)

  if (strcmp(p,n-›string) == 0) return n;

 if (ins == 0) error("name not found");

 name* nn = new name;

 nn-›string = new char[strlen(p) + 1];

 strcpy(nn-›string,p);

 nn-›value = 1;

 nn-›next = table[ii];

 table[ii] = nn;

 return nn;

}

inline name* insert(char* s) { return look (s,1); }

token_value get_token();

double term();

double expr()

{

 double left = term();

 for (;;)

  switch (curr_tok) {

  case PLUS:

   get_token();

   left += term();

   break;

  case MINUS:

   get_token();

   left -= term();

   break;

  default:

   return left;

  }

}

double prim();

double term()

{

 double left = prim();

 for (;;)

  switch (curr_tok) {

  case MUL:

   get_token();

   left *= prim();

   break;

  case DIV:

   get_token();

   double d = prim();

   if (d == 0) return error("divide by 0");

   left /= d;

   break;

  default:

   return left;

  }

}

int number_value;

char name_string[80];

double prim()

{

 switch (curr_tok) {

 case NUMBER:

  get_token();

  return number_value;

 case NAME:

  if (get_token() == ASSIGN) {

   name* n = insert(name_string);

   get_token();

   n-›value = expr();

   return n-›value;

  }

  return look(name_string)-›value;

 case MINUS:

  get_token();

  return -prim();

 case LP:

  get_token();

  double e = expr();

  if (curr_tok != RP) return error(") expected");

  get_token();

  return e;

 case END:

  return 1;

 default:

  return error ("primary expected");

 }

}

token_value get_token()

{

 char ch = 0;

 do {

  if (!cin.get(ch)) return curr_tok = END;

 } while (ch !='\n' && isspace(ch));

 switch (ch) {

 case ';':

 case '\n':

  cin ›› WS;

  return curr_tok=PRINT;

 case '*':

 case '/':

 case '+':

 case '-':

 case '(':

 case ')':

 case '=':

  return curr_tok=ch;

 case '0': case '1': case '2': case '3': case '4':

 case '5': case '6': case '7': case '8': case '9':

 case '.':

  cin.putback(ch);

  cin ›› number_value;

  return curr_tok=NUMBER;

 default:

  if (isalpha(ch)) {

   char* p = name_string;

   *p++ = ch;

   while (cin.get(ch) && isalnum(ch)) *p++ = ch;

   cin.putback(ch);

   *p = 0;

   return curr_tok=NAME;

  }

  error ("bad token");

  return curr_tok=PRINT;

 }

}

int main(int argc, char* argv[])

{

 switch (argc) {