Справочное руководство по C++

 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) {
 case 1:
 break;
 case 2:
 cin = *new istream(strlen(argv[1]),argv[1]);
 break;
 default:
 error("too many arguments");
 return 1;
 }

 // insert predefined names:
 insert("pi")-›value = 3.1415926535897932385;
 insert("e")-›value = 2.7182818284590452354;

 while (1) {
 get_token;
 if (curr_tok == END) break;
 if (curr_tok == PRINT) continue;
 cout ‹‹ expr ‹‹ "\n";
 }

 return no_of_errors;
}

b3_2_6a.cxx

extern void strcpy(char *,char *);
extern void exit(int);
extern int strlen(char *);

char *save_string(char* p)
{
 char* s = new char[strlen(p)+1];
 strcpy(s,p);
 return s;
}

int main (int argc, char* argv[])
{
 if (argc ‹ 2) exit(1);
 int size = strlen(argv[1])+1;
 char* p = save_string (argv[1]);
 delete[size] p;
}

b3_2_6b.cxx

#include ‹stream.hxx›

extern void exit(int);
void out_of_store
{

 cout ‹‹ "operator new failed: out of store\n";
 exit(1);
}

typedef void (*PF);

extern PF set_new_handler(PF);

main
{
 set_new_handler(&out_of_store);
 char *p = new char[100000000];
 cout ‹‹ "done, p = " ‹‹ long(p) ‹‹ "\n";
}

b4_6_8.cxx

// This version of the program does not assume sizeof(int) == sizeof(char*)!

#include ‹stream.hxx›
#include ‹stdarg.hxx›