How do I declare a struct within a class? - c++

Question

I want to declare a struct within a class which is private and I want to give a character value to a variable in the same struct, but I can't initialize it or cin it:
class puple
{
private:
struct p
{
char name[25];
int grade;
};
public:
puple(){};
void setme()
{
this->p::grade=99;
this->p::name[25]='g'; //here is the problem
}
void printme()
{
cout<<"Name: "<<this->p::name<<endl;
cout<<"Grade: "<<this->p::grade<<endl;
}
};
void main()
{
puple pu1;
pu1.setme();
pu1.printme();
}

Answer 1

You've describe a type called "p" which is a struct. There is yet no thing of type p around. Therefore your
p->...
calls make no sense.
Try declaring
p pInstance;
in your class and using it, ie:
void setme()
{
this->pInstance.grade=99;
this->pInstance.name[25]='g'; //here is the problem
}
Note even with this your assignment to name[25] will fail as the allowed indices for that array are 0 up to 24 (totalling 25 elements).

Answer 2

You have two serious problems here
struct p
{
char name[25];
int grade;
};
This defines a struct type, named p. I think what you wanted to do was
struct
{
char name[25];
int grade;
} p;
This will declare a struct, named p, with the name and grade member variables.
Your second serious problem is that you assign:
this->p::name[25]='g'; //here is the problem
This assigns 'g' to the 26th element of the array name. (arrays are 0-indexed)

Answer 3

isn't it
struct { ... } p; // variable of struct-type definition.
not
struct p { ... }; // type 'struct p' definition.
?

Answer 4

Place the struct definition outside of the class using a typedef. By having the struct defined in your .cpp file it will not be visible outside of your class.
#include <iostream>
typedef struct _foo
{
int a;
} foo;
class bar
{
public:
void setA(int newa);
int getA();
private:
foo myfoo;
};
void bar::setA(int newa)
{
myfoo.a = newa;
}
int bar::getA()
{
return myfoo.a;
}
using namespace std;
int main()
{
bar mybar;
mybar.setA(17);
cout << mybar.getA() << endl;
return 0;
}