Error in C++ code when overloading operators - c++

Question

I'm trying to overload the '+' and '=' operators in my code, but I keep getting a run time error and the program crashes when running using VS2012 but runs perfectly in borland C 3.1.
Here's my code:
class employee{
int eid;
long esalary;
char * ename;
static char company_name[20];
static int emp_count;
public:
static char * getcompanyname(){
return company_name;
}
static int getempcount(){
return emp_count;
}
void set(int empid);
void set(long empsalary);
void set(char empname[]);
int getid();
long getsalary();
char * getname();
employee(int empid=0,long empsalary=0,char empname[]="NA"){
eid=empid;
esalary=empsalary;
ename=new char[strlen(empname)+1];
strcpy(ename,empname);
emp_count++;
}
employee(employee &ref){
eid=ref.eid;
esalary=ref.esalary;
ename=new char(strlen(ref.ename)+1);
strcpy(ename,ref.ename);
}
~employee(){
delete(ename);
}
employee operator+(employee &ref){
employee temp(*this);
temp.esalary=esalary+ref.esalary;
return(temp);
}
employee& operator= (employee &ref){
eid=ref.eid;
esalary=ref.esalary;
return * this;
}
}e1,e2,emp;
then in main:
emp=e1+e2;

Answer 1

To be honest, your code is invalid. It should not even compile, since it violates the reference binding rules: the + operator returns a temporary object, which cannot be passed through a non-const reference to the = operator. If you managed to compile this code, it simply means that your compiler(s) accepts it as an "extension" of the language.
To fix that specific error you have to add a bunch of const qualifiers to your declarations
employee operator +(const employee &ref) const {
employee temp(*this);
temp.esalary = esalary + ref.esalary;
return temp;
}
employee& operator =(const employee &ref){
eid = ref.eid;
esalary = ref.esalary;
return *this;
}
This will make your code valid from the C++ point of view, but it probably won't fix the crash, since the reason for the crash must be elsewhere.
Here's your crash-causing error: in the copy-constructor you did this
ename=new char(strlen(ref.ename)+1);
When you allocate an array with new, you have to use [] brackets, not ()
ename = new char[strlen(ref.ename) + 1];
You did it correctly in your first constructor, but then you for some reason used () instead of [] in your copy constructor. () in this context mean something completely different: it allocates a single char and initializes it to strlen(ref.ename) + 1 value.
BTW, is there a reason you are not copying ename in the copy-assignment operator?
Also, memory allocated with new[] must be freed with delete[]. Not with delete, but with delete[]. This is what your destructor should look like
~employee() {
delete[] ename;
}
Finally, you might be much better off using std::string for storing ename, instead of relying on raw memory management. (Unless you were specifically asked to do it that way).