Бьярн Страустрап - Справочное руководство по C++

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

---

 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›

extern void exit(int);

void error (int …);

main(int argc, char* argv[])

{

 switch (argc) {

 case 1:

  error(0,argv[0],(char*)0);

  break;

 case 2:

  error(0,argv[0],argv[1],(char*)0);

  break;

 default:

  error(1,"with",dec(argc-1),"arguments",(char*)0);

 }

}

void error(int n …)

{

 va_list ap;

 va_start(ap,n);

 for (;;) {

  char *p = va_arg(ap,char*);

  if (p == 0) break;

  cerr ‹‹ p ‹‹ " ";

 }

 va_end(ap);

 cerr ‹‹ "\n";

 if (n) exit(n);

}

b4_6_9.cxx

#include ‹stream.hxx›

struct user {

 char *name;

 char* id;

 int dept;

};

typedef user* Puser;

user heads[] = {

 "Mcilroy M.D", "doug", 11271,

 "Aho A.V.", "ava", 11272,

 "Weinberger P.J.", "pjw", 11273,

 "Schryer N.L.", "nls", 11274,

 "Schryer N.L.", "nls", 11275,

 "Kernighan B.W.", "bwk", 11276

};

typedef int (*CFT)(char*,char*);

void sort(char* base, unsigned n, int sz, CFT cmp)

{

 for (int i=0; i‹n-1; i++)

  for (int j=n-1; i‹j; j--) {

   char* pj = base+j*sz;

   char *pj1 = pj-sz;

   if ((*cmp)(pj,pj1) ‹ 0)

    // swap b[j] and b[j-1]

    for (int k=0; k‹sz; k++) {

     char temp = pj[k];

     pj[k] = pj1[k];

     pj1[k] = temp;

    }

  }

}

void print_id(Puser v, int n)

{

 for (int i=0; i‹n; i++)

  cout ‹‹ v[i].name ‹‹ "\t"

   ‹‹ v[i].id ‹‹ "\t"

   ‹‹ v[i].dept ‹‹ "\n";

}

extern int strcmp(char*, char*);

int cmp1(char* p, char* q)

{

 return strcmp(Puser(p)-›name, Puser(q)-›name);

}

int cmp2(char* p, char* q)

{

 return Puser(p)-›dept - Puser(q)-›dept;

}

main ()

{

 sort((char*)heads,6,sizeof(user),cmp1);

 print_id(heads,6);

 cout ‹‹ "\n";

 sort ((char*)heads,6,sizeof(user),cmp2);

 print_id(heads,6); // in department number order

}

b5_3_2.cxx

#include ‹stream.hxx›

class intset {

 int cursize, maxsize;

 int *x;

public:

 intset(int m, int n);

 ~intset();

 int member(int t);

 void insert(int t);

 void iterate(int& i) { i = 0; }

 int ok(int& i) { return i‹cursize; }

 int next(int& i) { return x[i++]; }

};

extern void exit (int);

void error(char *s)

{

 cout ‹‹ "set: " ‹‹ s ‹‹ "\n";

 exit(1);

}

extern int atoi(char *);

extern int rand();

int randint (int u) // in the range 1…u

{

 int r = rand();

 if (r ‹ 0) r = -r;

 return 1 + r%u;

}

intset::intset(int m, int n)

{

 if (m‹1 || n‹m) error("illegal intset size");

 cursize = 0;

 maxsize = m;

 x = new int[maxsize];

}

intset::~intset()

{

 delete x;

}

void intset::insert(int t)

{

 if (++cursize › maxsize) error("too many elements");

 int i = cursize-1;

 x[i] = t;

while (i›0 && x[i-1]›x[i]) {

 int t = x[i];

 x[i] = x[i-1];

 x[i-1] = t;

 i--;

 }

}

int intset::member(int t)

{

 int l = 0;

 int u = cursize-1;

 int m =0;

 while (l ‹= u) {

  m = (l+u)/2;

  if (t ‹ x[m])

   u = m-1;

  else if (t › x[m])

   l = m+1;

  else

   return 1; // found

 }

 return 0; // not found

}

void print_in_order(intset* set)

{

 int var;

 set-›iterate(var);

 while (set-›ok(var)) cout ‹‹ set-›next(var) ‹‹ "\n";

}

main (int argc, char *argv[])

{

 if (argc!= 3) error("two arguments expected");

 int count = 0;

 int m = atoi(argv[1]);

 int n = atoi (argv[2]);

 intset s(m,n);

 int t = 0;

 while (count ‹m) {

  t = randint(n);

  if (s.member(t)==0) {

   s.insert(t);

   count++;

  }

 }

 print_in_order(&s);

}

b5_4_5.cxx

#include ‹stream.hxx›

struct cl

{

 char* val;

 void print(int x) { cout ‹‹ val ‹‹ x ‹‹ "\n"; }

 cl(char *v) { val = v; }

};

typedef void (cl::*PROC)(int);

main()

{

 cl z1("z1 ");

 cl z2("z2 ");

 PROC pf1 = &cl::print;

 PROC pf2 = &cl::print;

 z1.print(1);

 (z1.*pf1)(2);

 z2.print(3);

 ((&z2)-›*pf2)(4);

}

b5_5_3.cxx

main() {

 char *p = new char[100];

 char *q = new char[100];

 delete p;

 delete p;

}

b6_3_2.cxx

#include "stream.hxx"

int error (char * p)

{

 cout ‹‹ p ‹‹ "\n";

 return 1;

}

class tiny {

 char v;

 tiny assign(int i)

 {v  = (i&~63) ? (error("range error"),0) : i; return *this; }

public:

 tiny (int i) { assign(i); }

 tiny (tiny& t) { v = t.v; }

 tiny operator=(tiny& t1) { v = t1.v; return *this; }

 tiny operator=(int i) { return assign(i); }

 int operator int() { return v; }

};

void main()

{

 tiny c1 = 2;

 tiny c2 = 62;

 tiny c3 = (c2 - c1);

 tiny c4 = c3;

 int i = (c1 + c2);

 c1 = (c2 + (2 * c1));

 c2 = c1 - i;

 c3 = c2;

}

b6_6.cxx

#include ‹stream.hxx›

extern int strcpy(char*, char*);

extern int strlen(char *);

struct string {

 char *p;

 int size;

 inline string(int sz) { p = new char[size=sz]; }

 string(char *);

 inline ~string() { delete p; }

 void operator=(string&);

 string(string&);

};

string::string(char* s)

{

 p = new char [size = strlen(s) + 1];

 strcpy (p,s);

}

void string::operator=(string& a)

{

 if (this == &a) return;

 delete p;

 p=new char[size=a.size];

 strcpy(p,a.p);

}

string::string(string& a)

{

 p=new char[size=a.size];

 strcpy(p,a.p);

}

string g(string arg)

{

 return arg;

}

main()

{

 string s = "asdf";

 s = g(s);

 cout ‹‹ s.p ‹‹ "\n";

}

b6_7.cxx

#include ‹stream.hxx›

#include ‹string.h›