c++11 memcpy data from one int* to another int*

Question

I have a class:

class Kunde{
    char *name;
    char *ort;
    int *alter;
    double umsatz;
    int transaktion;
    int id=0;
    int dummyAlter=20;

    public:
    static int anzahl;

    Kunde(char* n=(char*)"Max Maier", char* o=(char*)"Köln", int *a=&dummyAlter);
    Kunde(const Kunde &k);
    ~Kunde();
    void buy(double u);
    static int getAnzahl();
};

In my .cpp-File I have:

 Kunde::Kunde(char* n, char* o, int *a)
    {
    name=n;
    ort=o;
    alter=a;
    id=anzahl++;
    umsatz=0;
    transaktion=0;
};

and I want to write a copying constructor.

This is achieved by:

 Kunde::Kunde(const Kunde &k)
 {
    int lenname=(int)strlen(k.name)+1;
    name=new char[lenname];
    memcpy(name, k.name, lenname);
    int lenort=(int)strlen(k.ort)+1;
    ort=new char[lenort];
    memcpy(ort, k.ort, lenort);

    alter=new int;
    memcpy(alter, k.alter, sizeof(int));

    id=k.id;
    anzahl++;
    umsatz=k.umsatz;
    transaktion=k.transaktion;
}

The code compiles just fine but when I execute it, it produces an error where I use memcpy to copy the data from k.alter to alter.

Do you see what is wrong? I tried stfw and rtfm but it seems I'm too stupid to find anything concerning "pure" int*'s instead of int*-Arrays.

Thanks for your time.

Answer 1

After some hints from you folks I finally found the problems.

1. First: I always tried to save the char*s directly (you see this in the constructor) and by that only achieved that I had pointers to my strings.

Solution:

Kunde::Kunde(char* n, char* o, int a)  
{
    int lenname=(int)strlen(n)+1;
    name=new char[lenname];
    memcpy(name, n, lenname);

    int lenort=(int)strlen(o)+1;
    ort=new char[lenort];
    memcpy(ort, o, lenort);

    alter=new int;
    *alter=a;
    id=anzahl++;
    umsatz=0;
    transaktion=0;
}

2. Second: I tried to use an int* as a parameter for the constructor which a) makes no sense and b) is a royal PITA. After I fixed my parameters I used the construct proposed by @Matthias247 to do the copying of the int-data.

Solution:

Kunde::Kunde(const Kunde &k) 
{
    int lenname=(int)strlen(k.name)+1;
    name=new char[lenname];
    memcpy(name, k.name, lenname);

    int lenort=(int)strlen(k.ort)+1;
    ort=new char[lenort];
    memcpy(ort, k.ort, lenort);

    alter=new int;
    *alter = *(k.alter);
    id=k.id;
    anzahl++;
    umsatz=k.umsatz;
    transaktion=k.transaktion;
}

Answer 2

Regarding your problem with the integer pointer, your problem is twofold: First you have the default argument in the constructor which is a pointer to the address 20, not a pointer to the value 20. The second problem is that you use the address-of operator in the memcpy call, it will give you the address of the pointer, i.e. you have an expression of type int **.