C++ and malloc

[Larry Lindsey]

Is there a better way of defining a large array other than malloc? I'm
looking to declare an array of bool at a length of up to 250000000. Thanks,

Larry

[Zeljko Vrba]

On 2003-09-29, Larry Lindsey <gt*****@prism.gatech.edu> wrote:

Is there a better way of defining a large array other than malloc? I'm
looking to declare an array of bool at a length of up to 250000000. Thanks,

bool *arr = new bool[250000000];
bool arr[250000000];

Or you might want to use std::bit_vector which should substantially save
space.

[Unforgiven]

Larry Lindsey wrote:

Is there a better way of defining a large array other than malloc?
I'm looking to declare an array of bool at a length of up to
250000000. Thanks,

That's a lotta bools...

Anyway:

bool *MyBools = new bool[250000000];
delete[] MyBools;

or even better:
#include <vector>
std::vector<bool> MyBools(250000000);

(Note that std::vector can grow and shrink dynamically, you don't have to
give it it's maximum size initially if you don't want to)

--
Unforgiven

"Most people make generalisations"
Freek de Jonge

[jeffc]

"Larry Lindsey" <gt*****@prism.gatech.edu> wrote in message
news:bl**********@news-int.gatech.edu...

Is there a better way of defining a large array other than malloc? I'm
looking to declare an array of bool at a length of up to 250000000.

Thanks,

I would use a standard library type such as vector.

[Steven C.]

"Larry Lindsey" <gt*****@prism.gatech.edu> wrote in message
news:bl**********@news-int.gatech.edu...
Is there a better way of defining a large array other than malloc? I'm
looking to declare an array of bool at a length of up to 250000000. Thanks,

Larry

__________________________________________________ _____

Since a bool hold is only 1 or 0 I use a long to store 32 bools and then you
could malloc (or new) 7812500 longs. It would be trival to wirte a class to
do this.

[Gianni Mariani]

Steven C. wrote:

"Larry Lindsey" <gt*****@prism.gatech.edu> wrote in message
news:bl**********@news-int.gatech.edu...
Is there a better way of defining a large array other than malloc? I'm
looking to declare an array of bool at a length of up to 250000000. Thanks,

Larry

__________________________________________________ _____

Since a bool hold is only 1 or 0 I use a long to store 32 bools and then you
could malloc (or new) 7812500 longs. It would be trival to wirte a class to
do this.

I believe vector<bool> is a special case for this.

[Steven C.]

"Gianni Mariani" <gi*******@mariani.ws> wrote in message
news:bl********@dispatch.concentric.net...
Steven C. wrote:

"Larry Lindsey" <gt*****@prism.gatech.edu> wrote in message
news:bl**********@news-int.gatech.edu...
Is there a better way of defining a large array other than malloc? I'm
looking to declare an array of bool at a length of up to 250000000. Thanks,
Larry

__________________________________________________ _____

Since a bool hold is only 1 or 0 I use a long to store 32 bools and then you could malloc (or new) 7812500 longs. It would be trival to wirte a class to do this.

I believe vector<bool> is a special case for this.

__________________________________________

Really that would be great.

[Mike Wahler]

"Steven C." <no****@xxx.com> wrote in message
news:mV******************@twister.socal.rr.com...

"Gianni Mariani" <gi*******@mariani.ws> wrote in message
news:bl********@dispatch.concentric.net...
Steven C. wrote:

"Larry Lindsey" <gt*****@prism.gatech.edu> wrote in message
news:bl**********@news-int.gatech.edu...
Is there a better way of defining a large array other than malloc? I'm
looking to declare an array of bool at a length of up to 250000000. Thanks,

Larry

__________________________________________________ _____

Since a bool hold is only 1 or 0 I use a long to store 32 bools and then

you

could malloc (or new) 7812500 longs. It would be trival to wirte a

class to

do this.

I believe vector<bool> is a special case for this.

__________________________________________

Really that would be great.

Not 'would', but 'is' :-)

================================================== =======
ISO/IEC 14882:1998(E)

23.2.5 Class vector<bool>

1 To optimize space allocation, a specialization of vector for
bool elements is provided:

namespace std {
template <class Allocator> class vector<bool, Allocator> {
public:
// types:
typedef bool const_reference;
typedef (implementation defined) iterator; // See 23.1
typedef (implementation defined) const_iterator; // See 23.1
typedef (implementation defined) size_type; // See 23.1
typedef (implementation defined) difference_type;// See 23.1
typedef bool value_type;
typedef Allocator allocator_type;
typedef (implementation defined) pointer;
typedef (implementation defined) const_pointer
typedef std::reverse_iterator<iterator> reverse_iterator;
typedef std::reverse_iterator<const_iterator>
const_reverse_iterator;

// bit reference:
class reference {
friend class vector;
reference();
public:
~reference();
operator bool() const;
reference& operator=(const bool x);
reference& operator=(const reference& x);
void flip(); // flips the bit
};

[member function descriptions omitted for brevity -- MKW]

2 reference is a class that simulates the behavior of references
of a single bit in vector<bool>.
================================================== =======

HTH,
-Mike

[Noah Roberts]

Mike Wahler, in reply, wrote:

I believe vector<bool> is a special case for this.

__________________________________________

Really that would be great.

Not 'would', but 'is' :-)

There is also std::bitset<number> which provides a different interface
to the same sort of structure.

NR