#include <iostream>
using namespace std;
class foo
{
public:
class jimbo
{
public:
int wassup = 74;
};
};
foo w;
int main()
{
cout << w.jimbo.wassup;
return 0;
}
Nested Classes/Sub-Classes in C++
Author
How do you nest classes in C++. Why doesn''t my code work?:
Okay, your "class foo { ... };" describes a foo class, but it does not create a foo object. To do that you had to create one with "foo w;" Similarly, your jimbo class in foo is being defined (accessable via foo::jimbo), but there is no actual object of type "jimbo" inside the foo class.
Author
Ohhh, so they should be separate. Like this:
#include <iostream>using namespace std;struct jimbo //I''m too lazy to type public{ int wassup = 47;};struct foo //might as well be struct{ jimbo nested;}parent;int main(){ cout << parent.nested.wassup; return 0;}
That will work, but those aren''t nested classes; you merely have one global class as a member of another.
Author
meh. Oh, and thanx for the clear up - time for my inner OO control freak to manifest! May there be constructers everywhere!(evil laugh).
Author
it doesn't work:
error:
It IS a C++ project, and I can think of nothing else.
EDIT: It's a bug in MinGW and Dev-C++.
[edited by - Drakkcon on May 19, 2004 7:43:54 AM]
edit: breaking tables
[edited by - SiCrane on May 19, 2004 5:14:19 PM]
error:
g++.exe -D__DEBUG__ -c Main.cpp -o Main.o -I"C:/Dev-Cpp/include/c++" -I"C:/Dev-Cpp/include/c++/mingw32" -I"C:/Dev-Cpp/include/c++/backward" -I"C:/Dev-Cpp/include" -I"C:/DX9bSDK/Include" -ansi -fsave-memoized -O3 -pg -g3C:/Dev-Cpp/include/c++/bits/locale_facets.tcc: In function `int std::__convert_from_v(char*, int, const char*, _Tv, int* const&, int) [with _Tv = long unsigned int]':C:/Dev-Cpp/include/c++/bits/locale_facets.tcc:720: instantiated from `_OutIter std::num_put<_CharT, _OutIter>::_M_convert_int(_OutIter, std::ios_base&, _CharT, char, char, _ValueT) const [with _ValueT = long unsigned int, _CharT = char, _OutIter = std::ostreambuf_iterator<char, std::char_traits<char> >]'C:/Dev-Cpp/include/c++/bits/locale_facets.tcc:899: instantiated from `_OutIter std::num_put<_CharT, _OutIter>::do_put(_OutIter, std::ios_base&, _CharT, long unsigned int) const [with _CharT = char, _OutIter = std::ostreambuf_iterator<char, std::char_traits<char> >]'C:/Dev-Cpp/include/c++/bits/locale_facets.h:745: instantiated from `_OutIter std::num_put<_CharT, _OutIter>::Put(_OutIter, std::ios_base&, _CharT, long unsigned int) const [with _CharT = char, _OutIter = std::ostreambuf_iterator<char, std::char_traits<char> >]'C:/Dev-Cpp/include/c++/bits/ostream.tcc:215: instantiated from `std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(long unsigned int) [with _CharT = char, _Traits = std::char_traits<char>]'C:/Dev-Cpp/include/c++/ostream:122: instantiated from `std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(int) [with _CharT = char, _Traits = std::char_traits<char>]'Main.cpp:19: instantiated from hereC:/Dev-Cpp/include/c++/bits/locale_facets.tcc:2070: `strdup' undeclared (first use this function)C:/Dev-Cpp/include/c++/bits/locale_facets.tcc:2070: (Each undeclared identifier is reported only once for each function it appears in.)make.exe: *** [Main.o] Error 1Execution terminated #include <iostream>using namespace std;class A{public: class B { public: int foo; } nestedB;}whatever;int main(){ whatever.nestedB.foo = 400; cout << whatever.nestedB.foo; return 0;} It IS a C++ project, and I can think of nothing else.
EDIT: It's a bug in MinGW and Dev-C++.
[edited by - Drakkcon on May 19, 2004 7:43:54 AM]
edit: breaking tables
[edited by - SiCrane on May 19, 2004 5:14:19 PM]
struct jimbo{ int wassup = 47;};Is not valid C++ code. You can't initialize an non-const non-static datamember like that. You'd have to either initialize the the value in the constructor of jimbo, or make wassup a static const datamember. In the case of the latter solution, you'd access the value like jimbo::wassup.
edit: nm you fixed that problem in your last post
[edited by - Polymorphic OOP on May 19, 2004 10:40:28 AM]
Weed!
--
You''re Welcome,
Rick Wong
- Google | Google for GameDev.net
class Outside{ public: Outside() : X(1) {} int X; class Inside { public: Inside() : Y(2) {} int Y; };};int main(){ Outside outside; Outside::Inside inside; cout << outside.X; // 1 cout << inside.Y; // 2 return 0;}--
You''re Welcome,
Rick Wong
- Google | Google for GameDev.net
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