Passing a multidimensional array between classes

Question

I know that you can pass a multidimensional array into a function using:

void Class1::foo(Bar bars[][10])
{
   // Do stuff
}

and that you could return a pointer to the first member in a single-dimensional array by using:

Bar* Clas2::getBars()
{
   return bars;  //Where bars is a member of a class
}

However when 'bars' is a multidimensional array, I get the error:

Cannot convert Bar (*)[10] to Bar* in return

Could someone clarify why this is occuring?

Vlad from Moscow · Accepted Answer · 2014-02-19 17:06:03Z

1

You should write as the compiler says

Bar (*)[10] Clas2::getBars()
{
   return bars;  //Where bars is a member of a class
}

You said correctly that "you could return a pointer to the first member in a .. array". The member or more precisely element of your two dimensional array is one dimensional array of type Bar [10]. The pointer to this element will look as Bar (*)[10]

Oh I am sorry indeed shall be as

Bar (* Clas2::getBars() )[10]
{
   return bars;  //Where bars is a member of a class
}

Or you can use typedef. For example

typedef Bar ( *BarPtr )[10];
BarPtr Clas2::getBars()
{
   return bars;  //Where bars is a member of a class
}

edited Feb 19, 2014 at 17:06

answered Feb 19, 2014 at 16:58

Vlad from Moscow

313k27 gold badges204 silver badges358 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Xemerau Over a year ago

When I do, I get the error: "unqualified-id before ')' token, and states that getBars() returns no type.

Vlad from Moscow Over a year ago

@Xemerau I updated my post. If you used a construction from the upadted post then what is the error and what construction did you use?

Xemerau Over a year ago

The error was coming from the solution you posted before the update, using typedef fixed it though. Thanks a ton.

HolyBlackCat · Accepted Answer · 2014-02-19 17:09:34Z

0

You should use:

Bar (*Clas2::getBars())[10]
{
    return bars;  //Where bars is a member of a class
}

or better looking way:

typedef Bar (*Bar10x10ptr)[10];

Bar10x10ptr Clas2::getBars()
{
    return bars;  //Where bars is a member of a class
}

edited Feb 19, 2014 at 17:09

answered Feb 19, 2014 at 17:03

HolyBlackCat

102k13 gold badges182 silver badges306 bronze badges

2 Comments

Xemerau Over a year ago

If I do this, i get an error indicating that 'getBars' is a declared as a function returning an array, which seems like what I wanted to do.

HolyBlackCat Over a year ago

On GCC it works fine. Try to test it with int instead of Bar. Or you can try this: Bar (*a)[10]; decltype(a) Clas2::getBars() { return bars; //Where bars is a member of a class }

Collectives™ on Stack Overflow

Passing a multidimensional array between classes

2 Answers 2

3 Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

3 Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related