delete object "couse" return crash

[artures]

Hi, my problem is:
I'm initializing object of class USER (whel pointer actually), adn then deleting it, and everything goes quite OK in the main, until I reach return 0; the windows is trigering a break point, my question, is why... and how to resolve this problem

Some code:

class USER
{
public:
    char* nickname;
    struct tm * first_contact;
    bool oper;
    bool admin;
 
    USER(char* nickname, bool operat, bool admin);
    ~USER(void);
};
 
USER::USER(char* nickname, bool operat, bool admin)
{
    this->admin = admin;
    this->oper = operat;
    this->nickname = nickname;
 
    time_t czas;
    ::time( & czas );
    this->first_contact = localtime( & czas );
}
 
 
USER::~USER(void)
{
    delete this->first_contact;
    delete this->nickname;
}
 
int main (void){
    char *a = new char[4];
    a[0] = 's';
    a[0] = 'a';
    a[0] = 'd';
    a[0] = 0;
 
    USER *s = new USER(a, 0, 0);
    delete s;
 
    system("pause");
    return 0;
}

using MS visual 2010
thanks for any help

[artures]

ok figured something out, when i comment
//delete this->first_contact;
it runs smothly, i get the dependence in new/delete number/usage, but what is happening whitch first_contact then, is it deleted, or is it still egzisting in memory? (after delete s)

[weaknessforcats]

first_contact was never allocated using a new operator. That means the compiler is responsible for deleting it and not you.

You can only delete what you allocate using the new operator.

[artures]

ok, but doesn't the function first_contact = localtime( & czas );
allocate this memory? or is it doing it some weard other way?

[weaknessforcats]

You tell me.

If localtime allocates on the heap, and you fail to free the returned pointer, there is a memory leak. Bad.
If localtime does not allocate on the heap and you delete the pointer. Bad.
If localtime does not allocate on the heap and you do not delete the pointer. Good.

Therefore, you have to use the returned pointer to access the members of the returned struct and to copy those members to your own struct tm. The object pointed at by the returned pointer is only valid until the next C library time function call.

An object referred to by a returned pointer is deleted when the function completes or you have a memory leak. That would give you no time to recover the data in the struct tm the returned pointer points at. The only way around this is for the function to use a static variable that sticks around until the next call to a C library time function.

So if you know there will never be another call in your code, or in any other code that includes your code, at any time in the future, then you can just store the pointer. This is not not a wise choice, this business of predicting the future, so I do recommend your own struct tm in your class to keep the result of your call to localtime.