when to use a struct

[sde]

ok, so my last question got me thinking .. when is it really appropriate to use a struct vs a class?

[joe_bruin]

it's always a good time to use structs! of course, i program in c most of the day, so i never use classes.

but really, a struct is a class with no private data and no member functions. so, if you are going to be manipulating the object's members directly, and don't need any real functions to handle it, a struct is probably appropriate. structs are also crucial where binary compatibility is required. reading and writing binary data to a file, using sockets and interprocess communication, and accessing hardware directly is very much the domain of structs.

on the other hand, where abstraction is key, code modularity and reuse, encapsulation of functionality, and maintaining interfaces is more important (usually true for large projects involving many developers), classes seems to be the popular thing.

[sde]

great, thanks joe!

[pe666o]

not much to add to what "joe_bruin" said about it.
In C++ struct and class are all the same.
different name for the same thing.
However if/when you go to C#.NET there is a difference. structs- value types class-reference type
so in C# there is difference when you use structs or classes for your data encapsulation.

[zlatnik]

There is a difference that neither person who posted so far mentioned- all members of a struct are public by default, and all members of a class are private by default. Right now I'm trying to decide when it is appropriate to use a struct in my code (I'm strictly a C++ programmer)- I guess I am not convinced it is ever a good idea, at least with objects that are written to and read from disk. I'm still undecided for certain though.

[DJMaze]

structures are great for two things:

1. easy understandable replacement for to much function parameters.

2. union data so that it can be accessed in different ways

#1 is also used by M$ a lot in Windows C functions just so that it easy to add additional function parameters without loosing viewability.
Have you ever seen functions with 30 parameters? I DID!

[landonmkelsey]

Originally Posted by zlatnik

There is a difference that neither person who posted so far mentioned- all members of a struct are public by default, and all members of a class are private by default. Right now I'm trying to decide when it is appropriate to use a struct in my code (I'm strictly a C++ programmer)- I guess I am not convinced it is ever a good idea, at least with objects that are written to and read from disk. I'm still undecided for certain though.

members of a struct are public by default and members of a class are private by default!

However a struct can have private members using

private:

there is no other difference!

As somebody pointed out, in C# structs are significantly different than classes!

Here is a stupid interview question I got once:

"is a class a struct?" answer is yes and no