2002-02-02 18:36:12 +00:00
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
2000-07-27 14:27:00 +00:00
< html >
< head >
2002-02-02 18:36:12 +00:00
< meta http-equiv = "Content-Type" content = "text/html; charset=iso-8859-1" >
2000-07-27 14:27:00 +00:00
< title > scoped_array< / title >
< / head >
< body bgcolor = "#FFFFFF" text = "#000000" >
2002-02-02 18:36:12 +00:00
< h1 > < img src = "../../c++boost.gif" alt = "c++boost.gif (8819 bytes)" align = "middle" width = "277" height = "86" > < a name = "scoped_array" > scoped_array< / a > class template< / h1 >
< p > The < b > scoped_array< / b > class template stores a pointer to a dynamically allocated
array. (Dynamically allocated arrays are allocated with the C++ < b > new[]< / b >
expression.) The array pointed to is guaranteed to be deleted,
either on destruction of the < b > scoped_array< / b > , or via an explicit < b > reset< / b > .< / p >
< p > The < b > scoped_array< / b > template is a simple solution for simple
needs. It supplies a basic " resource acquisition is
2001-05-10 16:00:49 +00:00
initialization" facility, without shared-ownership or transfer-of-ownership
2002-02-02 18:36:12 +00:00
semantics. Both its name and enforcement of semantics (by being
< a href = "../utility/utility.htm#class noncopyable" > noncopyable< / a > )
signal its intent to retain ownership solely within the current scope.
Because it is < a href = "../utility/utility.htm#class noncopyable" > noncopyable< / a > , it is
2001-05-10 16:00:49 +00:00
safer than < b > shared_array< / b > for pointers which should not be copied.< / p >
2002-02-02 18:36:12 +00:00
< p > Because < b > scoped_array< / b > is so simple, in its usual implementation
every operation is as fast as a built-in array pointer and it has no
2001-05-10 16:00:49 +00:00
more space overhead that a built-in array pointer.< / p >
2002-02-02 18:36:12 +00:00
< p > It cannot be used in C++ standard library containers.
See < a href = "shared_array.htm" > < b > shared_array< / b > < / a >
if < b > scoped_array< / b > does not meet your needs.< / p >
< p > It cannot correctly hold a pointer to a single object.
See < a href = "scoped_ptr.htm" > < b > scoped_ptr< / b > < / a >
2000-07-27 14:27:00 +00:00
for that usage.< / p >
2002-02-02 18:36:12 +00:00
< p > A < b > std::vector< / b > is an alternative to a < b > scoped_array< / b > that is
a bit heavier duty but far more flexible.
A < b > boost::array< / b > is an alternative that does not use dynamic allocation.< / p >
< p > The class template is parameterized on < b > T< / b > , the type of the object
pointed to. < b > T< / b > must meet the smart pointer
< a href = "smart_ptr.htm#Common requirements" > common requirements< / a > .< / p >
2000-07-27 14:27:00 +00:00
2002-02-02 18:36:12 +00:00
< h2 > Synopsis< / h2 >
2000-07-27 14:27:00 +00:00
2002-02-02 18:36:12 +00:00
< pre > namespace boost {
2000-07-27 14:27:00 +00:00
2002-02-02 18:36:12 +00:00
template< typename T> class scoped_array : < a href = "../utility/utility.htm#noncopyable" > noncopyable< / a > {
public:
typedef T < a href = "#element_type" > element_type< / a > ;
explicit < a href = "#ctor" > scoped_array< / a > (T * p = 0); // never throws
< a href = "#~scoped_array" > ~scoped_array< / a > (); // never throws
void < a href = "#reset" > reset< / a > (T * p = 0); // never throws
T & < a href = "#operator[]" > operator[]< / a > (std::size_t i) const; // never throws
T * < a href = "#get" > get< / a > () const; // never throws
void < a href = "#swap" > swap< / a > (scoped_array & b); // never throws
};
template< typename T> void < a href = "#free-swap" > swap< / a > (scoped_array< T> & a, scoped_array< T> & b); // never throws
2000-07-27 14:27:00 +00:00
}< / pre >
2002-02-02 18:36:12 +00:00
< h2 > Members< / h2 >
< h3 >
< a name = "element_type" > element_type< / a > < / h3 >
2000-07-27 14:27:00 +00:00
< pre > typedef T element_type;< / pre >
< p > Provides the type of the stored pointer.< / p >
2002-02-02 18:36:12 +00:00
< h3 > < a name = "ctor" > constructors< / a > < / h3 >
< pre > explicit scoped_array(T * p = 0); // never throws< / pre >
< p > Constructs a < b > scoped_array< / b > , storing a copy of < b > p< / b > , which must
have been allocated via a C++ < b > new< / b > [] expression or be 0.
< b > T< / b > is not required be a complete type.
See the smart pointer
< a href = "smart_ptr.htm#Common requirements" > common requirements< / a > .< / p >
< h3 > < a name = "~scoped_array" > destructor< / a > < / h3 >
< pre > ~scoped_array(); // never throws< / pre >
< p > Deletes the array pointed to by the stored pointer.
Note that < b > delete[]< / b > on a pointer with a value of 0 is harmless.
The guarantee that this does not throw exceptions depends on the requirement that the
deleted array's objects' destructors do not throw exceptions.
See the smart pointer < a href = "smart_ptr.htm#Common requirements" > common requirements< / a > .< / p >
< h3 > < a name = "reset" > reset< / a > < / h3 >
< pre > void reset(T * p = 0); // never throws< / pre >
2000-07-27 14:27:00 +00:00
< p > If p is not equal to the stored pointer, deletes the array pointed to by the
stored pointer and then stores a copy of p, which must have been allocated via a
2002-02-02 18:36:12 +00:00
C++ < b > new[]< / b > expression or be 0.
The guarantee that this does not throw exceptions depends on the requirement that the
deleted array's objects' destructors do not throw exceptions.
See the smart pointer < a href = "smart_ptr.htm#Common requirements" > common requirements< / a > .< / p >
< h3 > < a name = "operator[]" > subscripting< / a > < / h3 >
< pre > T & operator[](std::size_t i) const; // never throws< / pre >
< p > Returns a reference to element < b > i< / b > of the array pointed to by the
stored pointer.
Behavior is undefined and almost certainly undesirable if the stored pointer is 0,
or if < b > i< / b > is less than 0 or is greater than or equal to the number of elements
2000-07-27 14:27:00 +00:00
in the array.< / p >
2002-02-02 18:36:12 +00:00
< h3 > < a name = "get" > get< / a > < / h3 >
< pre > T * get() const; // never throws< / pre >
< p > Returns the stored pointer.
< b > T< / b > need not be a complete type.
See the smart pointer
< a href = "smart_ptr.htm#Common requirements" > common requirements< / a > .< / p >
< h3 > < a name = "swap" > swap< / a > < / h3 >
< pre > void swap(scoped_array & b); // never throws< / pre >
< p > Exchanges the contents of the two smart pointers.
< b > T< / b > need not be a complete type.
See the smart pointer
< a href = "smart_ptr.htm#Common requirements" > common requirements< / a > .< / p >
< h2 > < a name = "functions" > Free Functions< / a > < / h2 >
< h3 > < a name = "free-swap" > swap< / a > < / h3 >
< pre > template< typename T> void swap(scoped_array< T> & a, scoped_array< T> & b); // never throws< / pre >
< p > Equivalent to < b > a.swap(b)< / b > . Matches the interface of < b > std::swap< / b > .
Provided as an aid to generic programming.< / p >
2000-07-27 14:27:00 +00:00
< hr >
2002-02-02 18:36:12 +00:00
< p > Revised <!-- webbot bot="Timestamp" S - Type="EDITED" S - Format="%d %B %Y" startspan --> 1 February 2002<!-- webbot bot="Timestamp" endspan i - checksum="13964" --> < / p >
< p > Copyright 1999 Greg Colvin and Beman Dawes. Copyright 2002 Darin Adler.
Permission to copy, use, modify, sell and distribute this document is granted
provided this copyright notice appears in all copies.
This document is provided " as is" without express or implied warranty,
and with no claim as to its suitability for any purpose.< / p >
2000-07-27 14:27:00 +00:00
< / body >
< / html >
