Compilation error appears because of missing const?

Question

I am trying to run a code that defines objects that are a collection of English letters. I dont know why it does not compile.

I have tried to change from int to const int but it is not the case,

and also added the disable 4996 message but it didnt help.

#include <iostream>

using namespace std;


class CharSet
{
    int size;
    char* pSet;
public:
    // -----------------------------------
    CharSet(int const size, char* set)
    {
        this->size = size;
        pSet = new char[strlen(set) + 1];
        strcpy(pSet, set);
    }
    // -----------------------------------

    ~CharSet()
    {
        delete[] pSet;
    }
    // -----------------------------------

    CharSet operator*(const CharSet & other)
    {
        int maxSize = 0;
        if (this->size >= other.size)
            maxSize = this->size;
        else
            maxSize = other.size;

        char * ret = new char[maxSize + 1];
        char temp;
        int index = 0;
        for (int i = 0; i < this->size; i++)
        {
            temp = this->pSet[i];
            for (int j = 0; j < other.size; j++)
            {
                if (other.pSet[j] == temp)
                {
                    ret[index] = temp;
                    index++;
                }
            }
        }
        ret[index] = '\0';

        return CharSet(maxSize, ret);
    }

    // -----------------------------------

    bool operator()(char check)
    {
        bool flag = false;
        for (int i = 0; i < this->size; i++)
        {
            if (pSet[i] == check)
                flag = true;
        }
        return flag;
    }

    // -----------------------------------

    friend ostream& operator<<(ostream& os, const CharSet& s)
    {
        os << s.pSet;
        return os;
    }

    // -----------------------------------
};

int main()
{
    CharSet s1(4, "DAQP"), s2(3, "AXZ");
    cout << s1 * s2 << endl;
    if (s1('Q') == true)
        cout << "The element is member of the set" << endl;
    else
        cout << "The element is not member of the set" << endl;
    return 0;
}

errors:

1. E0289 no instance of constructor "CharSet::CharSet" matches the argument
2. E0289 no instance of constructor "CharSet::CharSet" matches the argument list
3. C4996 'strcpy': This function or variable may be unsafe. Consider using strcpy_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details.
4. C2664 'CharSet::CharSet(const CharSet &)': cannot convert argument 2 from
5. C2664 'CharSet::CharSet(const CharSet &)': cannot convert argument 2 from 'const char [4]' to 'char *'

Answer 1

you need a const char* in your constructor:

CharSet(int const size, const char* set)

Thanks to @holy black cat "DAQP" is a const char[] which you didn't provide a constructor for that(the array will implicitly convert to pointer).

---

A better way is using std::string:

class CharSet
{
 std::string pSet;
public:
// -----------------------------------
CharSet(std::string set) : pSet(set)
{
}
// -----------------------------------

~CharSet()
{
}
// -----------------------------------

CharSet operator*(const CharSet & other)
{
    int maxSize = 0;

    std::string ret;
    char temp;
    int index = 0;
    for (int i = 0; i < pSet.size(); i++)
    {
        temp = pSet[i];
        for (int j = 0; j < other.pSet.size(); j++)
        {
            if (other.pSet[j] == temp)
            {
                ret += temp;
                index++;
            }
        }
    }
    return CharSet(ret);
}
// the rest of members ...
//
};

full code at godblot