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The CICA Windows Explosion!
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11
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FRAMIS.CPP
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C/C++ Source or Header
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1995-02-23
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3KB
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89 lines
// File from page 485 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).
//////////////////////////////////////////////////
//: FRAMIS.CPP -- Local overloaded new & delete
#include <stddef.h> // Size_t
#include <fstream.h>
ofstream out("framis.out");
class framis {
char c[10];
public:
framis() { out << "framis()\n"; }
~framis() { out << "~framis() ... "; }
void* operator new(size_t);
void operator delete(void*);
};
const psize = 100; // Number of frami allowed
unsigned char pool[psize * sizeof(framis)];
// Allocation map:
unsigned char alloc_map[psize] = {0};
// Size is ignored -- assume a framis object
void* framis::operator new(size_t) {
for(int i = 0; i < psize; i++)
if(!alloc_map[i]) {
out << "using block " << i << " ... ";
alloc_map[i] = 1; // Mark it used
return pool + (i * sizeof(framis));
}
out << "out of memory" << endl;
return 0;
}
void framis::operator delete(void* m) {
if(!m) return; // Check for null pointer
// Assume it was created in the pool
// Calculate which block number it is:
unsigned long block = (unsigned long)m
- (unsigned long)pool;
block /= sizeof(framis);
out << "freeing block " << block << endl;
// Mark it free:
alloc_map[block] = 0;
}
main() {
framis* f[psize];
for(int i = 0; i < psize; i++)
f[i] = new framis;
new framis; // Out of memory
delete f[10];
f[10] = 0;
// Use released memory:
framis* x = new framis;
delete x;
for(int j = 0; j < psize; j++)
delete f[j]; // Delete f[10] OK
}