Difference between C++ Structures and C++ Classes

[Subramaniam s V]

Hi All, Can anybody tell me the exact "Difference between C++ Structures and C++ Classes". I came to know that, apart from the access specifier Public(Structures) and Private(Classes) there is no other difference. Is that so? In that case why do they have 2 difference entities namely Structure and Classes with similar functionality?? Kindly clarify.

[includeh10]

I guess people who created C++ like the name "class".

[Chris Losinger]

Subramaniam s.V. wrote:

In that case why do they have 2 difference entities namely Structure and Classes with similar functionality?

'struct' allows for backwards-compatibility with C edit: what about this deserves a '1' vote? -- modified at 15:09 Tuesday 8th August, 2006

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[Naveen]

Then why class were created?? struct itself is enough ..na?

nave

[Amar Sutar]

Default inheritance type: a struct entails public inheritance by default whereas a class entails private inheritance. Regards Amar:)

[David Crow]

Subramaniam s.V. wrote:

Can anybody tell me the exact "Difference between C++ Structures and C++ Classes".

This is discussed in The Design and Evolution of C++.

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[Viorel]

About differences. The default protection in case of class is "private", whereas in case of struct it is "public":

class A
{
int a; // a is private
. . .
}; 

struct A
{
int a; // a is public
. . .
}; 

The default inheritance protection in case of class is "private", whereas in case of struct it is "public":

class B : A // is similar to "class B : private A"
{
};

struct B : A // is similar to "struct B : public A"
{
};

That’s my opinion about differences.

[Chris Losinger]

'class' is proper OO terminology, 'struct' isn't. but default member access isn't the only difference between struct and class: you can't use templates on structs - only on classes . a 'class' is intended to be the primary object type. 'struct' is for backwards compatibility. and, yes they overlap .

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[Hamid Taebi]

See The difference between structs and classes[^]

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WhiteSky

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[Zac Howland]

struct and class in C++ are identical with the exception of their default visibility (private for class, public for struct). The struct keyword was a leftover from the C lineage of C++. That said, when a C++ compiler sees the struct keyword, it will compile it, but not in the same way that a C compiler would have. The C++ compiler will generate a default constructor, destructor, and copy-assignment operator (whereas a C compiler would just treat it as a new datatype). They both exist in C++ because of the desire to be able to compile C code with a C++ compiler. Removing keywords such as this would have made such backwards-compatability impossible without first modifying the codebase.

If you decide to become a software engineer, you are signing up to have a 1/2" piece of silicon tell you exactly how stupid you really are for 8 hours a day, 5 days a week Zac

[Nemanja Trifunovic]

Chris Losinger wrote:

you can't use templates on structs - only on classes .

If you mean you can't use struct keyword inside of a template declaration, you are right. However, it is perfectly possible to make struct templates.

Programming Blog utf8-cpp

[Chris Losinger]

right. template < struct T > class nope {...}; = bad

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