>I wanted to know if the constuctor is coded correctly

No, because the assignments to stidnum, grades and totnumgrades will assign values to the arguments passed in, and I think your intent is to initialise the member attributes.

If we rewrite the constructor as:
Code:
Student::Student(int quux,double gronk[5],int snert)
{     
}
then would you assign to quux, gronk and snert, or still to stidnum, grades and totnumgrades, and if the latter three, why?

> Also, since I need to declare the member functions could someone please give me an example of how to declare the function using the class Student.

What's wrong with the ones you've already got? i.e.:
Code:
class Student
{
//...
             int studentid(int);
             double testgrade(double);
             double average(double);
//...
};