在C ++中实现octets类的Set

Question

I have an OOP assignment that says:

You are asked to implement a C++ class to model a set of octets (unsigned 8 bit numbers often referred to as bytes). The class is to be used in an embedded application that cannot assume the presence of the STL and must also use the smallest amount of storage possible (for the worst case of a full set) while being as efficient as possible during execution. Your class should have the appropriate constructors and destructor; in addition to implementing methods that allow the class user to add and remove numbers to/from the set, and check if a number belongs to the set. Once more, your set class should be self contained and should not use the C++ STL library but should be based on built-in C++ types.You are also asked to implement a main program that uses your class to demonstrate the above interfaces.

Here is my set.h file:

// File: Set.h

#ifndef SET_H
#define SET_H

// Specification of the class

class Set
{
private:
    int memory[8];

public:
    Set(); // Constructor 
    ~Set(); // Destructor 

    void add(int i); // Add number to a set
    bool find(int i); // Checks if a number belongs to a set
    void remove(int i);// Remove number from a set
};


#endif

and my set.cpp file

// File: Set.cpp


#include <iostream>
#include "Set.h"

Set::Set(){ // Constructor 
    for (int x = 0; x <8; x++)
        memory[x] = 0;
};

void Set::add(int i) // Add integer i to a set
{
    if (find(i)){

        int index = i / 32;
        int bit = i % 32;
        memory[index] +=  1<< bit ;
    }
}

bool Set::find(int i) // Checks if integer i belongs to a set. Returns true if yes
{

    int index = i / 32;
    int bit = i % 32;
    int temp = (memory[index] >> bit)%2;
    return temp;

}

void Set::remove(int i) // Remove integer i from a set
{

    if (find(i)){

        int index = i / 32;
        int bit = i % 32;
        memory[index] -= 1 << bit;

    }
}

I tried to implement a simple main file to test the class as follows:

// File: Setmain.cpp
// Test file for the Set class

#include <iostream>
#include "Set.cpp"

using namespace std;

int main(){

    Set test;
    test.add(200);

    return 0;

}

And I got these errors and I don't know how to solve them, any help would be appreciated

error LNK2005: "public: __thiscall Set::Set(void)" (??0Set@@QAE@XZ) already defined in Set.obj  

error LNK2005: "public: void __thiscall Set::add(int)" (?add@Set@@QAEXH@Z) already defined in Set.obj

error LNK2005: "public: bool __thiscall Set::find(int)" (?find@Set@@QAE_NH@Z) already defined in Set.obj

error LNK2005: "public: void __thiscall Set::remove(int)" (?remove@Set@@QAEXH@Z) already defined in Set.obj

error LNK2019: unresolved external symbol "public: __thiscall Set::~Set(void)" (??1Set@@QAE@XZ) referenced in function _main    

error LNK1120: 1 unresolved externals   

Thanks in advance

Answer 1

改变你的主要

#include "Set.h"

Answer 2

When I duplicated your code, I only got ONE error, similar to the last one in your list above (I am running g++ under Linux/Fedora). Once I define the Destructor function Set::~Set(void) (as an empty function), the compile worked.

Set::~Set(void) { // Destructor 
};

Aside from that, in terms of best programming practices, I would recommend some range-checking, and in terms of code efficiency, I would recommend using a shift operator (i >> 5) instead of division (i / 32), and using a mask operation (i & 0x1F) instead of modulo (i % 32). One would hope that a good optimizing compiler would produce the same code either way, but why chance it?

Answer 3

1. In setmain.cpp, change

    #include "Set.cpp" 

   to

    #include "Set.h" 

2. In set.cpp, implement a destructor

    Set::~Set() { }