struct vs class

[javaguy1]

im fairly new to C++ and learned Java first. im wondering when and why i would choose to use a struct over a class.

 

[bcravens]

If I remember correctly a struct can contain only data objects, but a class can contain data objects (properties) and methods.

 

[chipperMDW]

No, a struct can have anything a class can.

The one and only difference is that, if you have a member declared before you use public, private, or protected, it defaults to public in a struct and private in a class.

Otherwise, there's absolutely no functional difference between a struct and a class.

Typically, you use a struct when you have something that's intended to be POD (plain-old data) or to clearly indicate that all its members are public (or even that it has no members). You could just as easily use a class and just declare everything public, but using struct is often clearer and requires less typing.

 

[palbano]

another common use of struct is to define an interface.

struct car{
  virtual float getTopspeed()=0;
  virtual int getdoors()=0;
  virtual int getHorsepower()=0;
};

-pete

 

[xwb]

struct {
...
};

is the same as

class {
public:
...
};

I normally use struct if the code has to work in C as well and class if it is purely C++.

However, if you are working on a site which uses C# as well, be careful: in C#, struct is created on the stack, class is created on the heap.

 

[Zyrenthian]

One side note

struct
{
int a,b,c;
constructor
destructor
functions
};

class
{

constructor
destructor
functions
...
int a,b,c;
}

sizeof(struct) will be the sizeof the datamembers but the sizeof(class) may not. Useful when you want to dump the struct to a file and read it back in (in the no class or pointer situtation).

Matt