A QUICK C++ Question

[Kenji4861]

I have a class say, it's called student
and the student has

int grades[20];
int GPA;
char grade;

and say I have it declared by
studentA = *new student();

If I want to change the array size of the grades array? How can I do that?
Thanks!

 

[Platypus]

On the fly or in the code? Try using a vector.

 

[bUnMaNGo]

well I guess you can have something like int *grades; and int arraysize; and before you create a new student, prompt for the grade array size and set it dynamically? like in the constructor set grades = new int[arraysize] or something like that? I forget the exact syntax. I don't know if it's what you want though... sounds like you want to be able to change the size and insert more grades as time goes on.

 

[Platypus]

I'd definetly use a vector, it is a lot smarter, and can be updated as your data size grows, rather than having to recompile.

 

[notfred]

make this line:
int grades[20];
into this line:
int grades[200];


only way, otherwise you've got a lot more work than just a simple array.
Either that, or use a language with dynamic arrays

 

[Kenji4861]

Someone clued me in class that I'm suppose to "delete" the array portion and just declare the array portion. I'm not quite sure if that's possible.

 

[Ameesh]

just declare the grades array as a pointer and malloc the size of memory you need for the array like this:




class student{

public:

int * grades
double GPA
char GRADE


}



student * studentA = new Student();


studentA->grades = new int[SIZE_YOU_WANT];




you could also overload the constructer to make it nice and let the constructor take the number of grades the student got.



a vector is not the answer, learn your pointers and dynamic allocation.

 

[Ameesh]

<< Someone clued me in class that I'm suppose to "delete" the array portion and just declare the array portion. I'm not quite sure if that's possible. >>



you cannot deleted a staticlly allocated array only a dyanmically allocated one.

 

[crypticlogin]

<< a vector is not the answer, learn your pointers and dynamic allocation. >>


I think that would depend on how often, if at all, the array would need to be adjusted, and how the grades are entered (do I know how many grades there are beforehand?). Since Kenji4861 hasn't made that clear, I think either way is acceptable until more of the program is revealed.

edit: and I'd consider making some of those variables private, but hey that's just me.