pr11029.cpp

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////////////////////////////////////////
// File Name: pr11029.cpp
////////////////////////////////////////
#include <iostream>
#include <cstring>
#include <cstddef>
#include <new>

const int maxnames = 5;

////////////////////////////////////////
// The Names class.
////////////////////////////////////////
class Names
{
    char name[25];
    static char Names::pool[];
    static bool Names::inuse[maxnames];

public:
    Names(char* s)
        { std::strncpy(name, s, sizeof(name)); }
    void* operator new(size_t) throw(bad_alloc);
    void operator delete(void*) throw();
    void display() const
        { std::cout << name << std::endl; }
};

// Simple memory pool to handle fixed number of Names.
char Names::pool[maxnames * sizeof(Names)];
bool Names::inuse[maxnames];

// Overloaded new operator for the Names class.
void* Names::operator new(size_t) throw(bad_alloc)
{
    for (int p = 0; p < maxnames; p++)
    {
        if (!inuse[p])
        {
            inuse[p] = true;
            return pool+p*sizeof(Names);
        }
    }
    throw bad_alloc();
}

// Overloaded delete operator for the Names class.
void Names::operator delete(void* p) throw()
{
    if (p != 0)
        inuse[((char*)p - pool) / sizeof(Names)] = false;
}

////////////////////////////////////////
// The main() function.
////////////////////////////////////////
int main()
{
    Names* nm[maxnames];
    int i;

    for (i = 0; i < maxnames; i++)
    {
        std::cout << std::endl << "Enter name # "
                  << i+1 << ": ";
        char name[25];
        std::cin >> name;
        nm[i] = new Names(name);
    }

    for (i = 0; i < maxnames; i++)
    {
        nm[i]->display();
        delete nm[i];
    }

    return 0;
}