Question

I`m writing string class by myself. And I dont know how to write Сopy constructor.
I have such code.

class S { 
         private:
            char *string;
            int l;
         public:   
            S::S(const S &s){
                 string = new char[l+1];
                 memcpy(string,s.string,l+1);
               }
};

Complier didn`t give any errors, but .exe closed by unknown error. I tried it to use in main() function.

S pop("Q6");
S str(pop);

So I`m looking forward to your help.

Answer 1

In your copy constructor

 string = new char[l+1]

l hasn’t been initialized yet to to the length of the string, so it could be any value. You should initialize it (by copying the value from s.l) prior to using it.