Question

I have a class User that looks like this:

class User
{
    private:
        char* p_username;
        int nProcesses; 
        struct time
        {
            int mins;
            int secs;
        } totalTime;        
        int longestPID;     
        char* p_longestPath;    
    public:
        User();
        User(const char[],int,int,int,const char[]);
        ~User();
        User operator=(const User&);
        // Other functions
};

And the overloaded assignment operator function is:

User User::operator=(const User &u)
{
    if (this != &u)
    {
        delete [] p_username;
        delete [] p_longestPath;
        p_username = new char[strlen(u.p_username)+1];
        strcpy(p_username,u.p_username);
        nProcesses = u.nProcesses;
        totalTime.mins = u.totalTime.mins;
        totalTime.secs = u.totalTime.secs;
        longestPID = u.longestPID;
        p_longestPath = new char[strlen(u.p_longestPath)+1];
        strcpy(p_longestPath,u.p_longestPath);
    }
    return *this;
}

A sample main program using the assignment operator:

int main()
{
    cout << "\n\nProgram\n\n";

    User u("Username",20,30,112233,"Pathname"),u2;
    u2 = u;
}

When I try to use the assignment operator in the line u2 = u, everything is assigned properly except the dynamic char arrays.

Test output from the end of the operator= function shows that at the end of the assignment itself everything has works perfectly (the usernames and pathnames are correct), however test output from the main function directly after the assignment shows that all of a sudden the char arrays have changed. Suddenly the username of u2 is empty, and the first half of the pathname is garbage.

If at the end of the assignment operator function the username and pathname are perfect, how can they be wrong back in the calling function?

This really has me stumped…

Edit: Here are the constructors

User::User()
{
    p_username = 0;
    nProcesses = 0;
    totalTime.mins = 0;
    totalTime.secs = 0;
    longestPID = -1;
    p_longestPath = 0;
}


User::User(const char UID[],int minutes,int seconds,int PID,const char path[])
{
    p_username = new char[strlen(UID)+1];
    strcpy(p_username,UID);
    nProcesses = 1; 
    totalTime.mins = minutes;
    totalTime.secs = seconds;
    longestPID = PID;
    p_longestPath = new char[strlen(path)+1];
    strcpy(p_longestPath,path);
}

Answer 1

You are returning by value from the assignment function. It is possible that your copy constructor is flawed.