C - struct vs class

Question

Possible Duplicates    C C   Struct vs Class   What are POD types in C          Hi   In the C   In a Nutshell book  in chapter 6  classes  unders Access specifiers  mentioned the following      In a class definition  the default   access for members and base classes is   private  In a struct definition  the   default is public  That is the only   difference between a class and a   struct  although by convention  some   programmers use struct only for POD   classes and use class for all other   classes    My questions here are    Isn t there another difference between classes and structs in that structs don t hold functions and just hold data  What are POD classes  And  what is meant by all other classes here  Are there then special classes    Thanks

User · Answer

The other difference is that  template lt class T gt        is allowed  but  template lt struct T gt        is not

User · Answer

1  It is the only difference in C     2  POD  plain old data Other classes -  not POD

User · Answer

You could prove to yourself that there is no other difference by trying to define a function in a struct   I remember even my college professor who was teaching about structs and classes in C   was surprised to learn this  after being corrected by a student    I believe it  though   It was kind of amusing   The professor kept saying what the differences were and the student kept saying  actually you can do that in a struct too    Finally the prof  asked  OK  what is the difference  and the student informed him that the only difference was the default accessibility of members   A quick Google search suggests that POD stands for  Plain Old Data

User · Answer

Ok  POD means plain old data  That usually refers to structs without any methods because these types are then used to structure multiple data that belong together   As for structs not having methods  I have seen more than once that a struct had methods  and I don t feel that this would be unnatural

User · Answer

POD classes are Plain-Old data classes that have only data members and nothing else  There are a few questions on stackoverflow about the same  Find one here    Also  you can have functions as members of structs in C   but not in C  You need to have pointers to functions as members in structs in C

[c++] C++ - struct vs. class

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