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SMARTP.CPP
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1995-02-23
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// File from page 424 in "Thinking in C++" by Bruce Eckel
//////////////////////////////////////////////////
// From the compressed package ECKELT01.ZIP 2/21/95
// Copyright (c) Bruce Eckel, 1995
// Source code file from the book "Thinking in C++",
// Prentice Hall, 1995, ISBN: 0-13-917709-4
// All rights reserved EXCEPT as allowed by the following
// statements: You may freely use this file for your own
// work, including modifications and distribution in
// executable form only. You may copy and distribute this
// file, as long as it is only distributed in the complete
// (compressed) package with the other files from this
// book and you do not remove this copyright and notice.
// You may not distribute modified versions of the source
// code in this package. This package may be freely placed
// on bulletin boards, internet nodes, shareware disks and
// product vendor disks. You may not use this file in
// printed media without the express permission of the
// author. Bruce Eckel makes no
// representation about the suitability of this software
// for any purpose. It is provided "as is" without express
// or implied warranty of any kind. The entire risk as to
// the quality and performance of the software is with
// you. Should the software prove defective, you assume
// the cost of all necessary servicing, repair, or
// correction.
// If you think you've found an error, please
// email all modified files with loudly commented changes
// to: eckel@aol.com (please use the same
// address for non-code errors found in the book).
//////////////////////////////////////////////////
//: SMARTP.CPP -- Smart pointer example
#include <iostream.h>
#include <string.h>
class obj {
static int i, j;
public:
void f() { cout << i++ << endl; }
void g() { cout << j++ << endl; }
};
// Static member definitions:
int obj::i = 47;
int obj::j = 11;
// Container:
class obj_container {
enum { sz = 100 };
obj* a[sz];
int index;
public:
obj_container() {
index = 0;
memset(a, 0, sz * sizeof(obj*));
}
void add(obj* OBJ) {
if(index >= sz) return;
a[index++] = OBJ;
}
friend class sp;
};
// Iterator:
class sp {
obj_container* oc;
int index;
public:
sp(obj_container* OC) {
index = 0;
oc = OC;
}
// Return value indicates end of list:
int operator++() { // Prefix
if(index >= oc->sz) return 0;
if(oc->a[++index] == 0) return 0;
return 1;
}
int operator++(int) { // Postfix
return operator++(); // Use prefix version
}
obj* operator->() const {
if(oc->a[index]) return oc->a[index];
static obj dummy;
return &dummy;
}
};
main() {
const sz = 10;
obj o[sz];
obj_container OC;
for(int i = 0; i < sz; i++)
OC.add(&o[i]); // Fill it up
sp SP(&OC); // Create an iterator
do {
SP->f(); // Smart pointer calls
SP->g();
} while(SP++);
}