Pointer question
 

Hey guys, I was just wondering when using classes to obtain a name or something like that when a pointer is used how come you don't have to use the new and delete key words.

class LibBook



{

    private:

       char *name

    public:

       LibBook( char* = '\0')

       void showBookName()



};

Thanks in advance.

Re: Pointer question
 

Generally you do. Do you have a more specific example? The one you posted is not really correct. The '\0' should be 0.

Re: Pointer question
 

I found another example:

class Date

{

 private:

         char day[10];

         char month[10];

         int year;

  

public:

        



        void set(char* day, char* month, int year);

  

        void display(Date datem);

  

        char* get_day();



        char* get_month();



        int get_year();



 };



void Date::set(char* d, char* m, int y)

{



        strncpy(day, d, 9);

        strncpy(month, m, 9);

        year=y;



}



  

void Date::display(Date date)

{

        cout << "The day is ";

        cout << date.get_day();

        

        cout << "\nThe month is ";

        cout << date.get_month();

        

        cout << "\nThe year is ";

        cout << date.get_year();

        cout << endl;

}

  

char* Date::get_day()

{

        return day;

}



char* Date::get_month()

{

        return month;

}



int Date::get_year()

{

        return year;

}

Re: Pointer question
 

What is your question in regard to pointers about your last posted code? The functions that return a pointer to the beginning of a char array that is private? Or the function parameters that receive a pointer to the beginning of a string to copy?

Re: Pointer question
 

I was just wondering with the variables such as day and month as they are pointers how come the new and delete keywords don't have to be used.

Re: Pointer question
 

The day and month variables are declared to be arrays of length 10. You only need to use new and delete[] if the arrays have not been allocated yet.

Hi Dave, I was under the impression that '\0' was equal to 0?
I got the output "equal" for the following program.

#include <cstdio>



int main()

{

  if ( '\0' == 0 )

    printf( "equal" );

  getchar();

}

Or is this only restricted to my compiler (mingw)?

Re: Pointer question
 

Thanks for your help Dave & Dante.

Re: Pointer question
 

It was more of a hint not to get into the habit of writing characters to pointers and confusing NULL and '\0'.

[edit]So yes, I overstated things when I said it wasn't quite correct.

Re: Pointer question
 

Ah I see. Yes, one should generally initialize pointers to 0 instead of '\0' to avoid confusion. The Great One himself recommends it as well.