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| <h1><A href="../../index.htm"><img src="../../boost.png" alt="boost.png (6897 bytes)" align="middle" width="277" height="86" |
| border="0"></A>scoped_array 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 initialization" facility, without |
| shared-ownership or transfer-of-ownership 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 safer than <b>shared_array</b> for pointers which should not be copied.</p> |
| <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 more space |
| overhead that a built-in array pointer.</p> |
| <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> |
| for that usage.</p> |
| <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> |
| <h2>Synopsis</h2> |
| <pre>namespace boost { |
| |
| template<class T> class scoped_array : <a href="../utility/utility.htm#Class_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="#destructor">~scoped_array</a>(); // never throws |
| |
| void <a href="#reset">reset</a>(T * p = 0); // never throws |
| |
| T & <a href="#operator[]">operator[]</a>(std::ptrdiff_t i) const; // never throws |
| T * <a href="#get">get</a>() const; // never throws |
| |
| operator <A href="#conversions" ><i>unspecified-bool-type</i></A>() const; // never throws |
| |
| void <a href="#swap">swap</a>(scoped_array & b); // never throws |
| }; |
| |
| template<class T> void <a href="#free-swap">swap</a>(scoped_array<T> & a, scoped_array<T> & b); // never throws |
| |
| }</pre> |
| <h2>Members</h2> |
| <h3> |
| <a name="element_type">element_type</a></h3> |
| <pre>typedef T element_type;</pre> |
| <p>Provides the type of the stored pointer.</p> |
| <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="destructor">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> |
| <p> |
| Deletes the array pointed to by the stored pointer and then stores a copy of p, |
| which must have been allocated via a 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::ptrdiff_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 in the array.</p> |
| <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="conversions">conversions</a></h3> |
| <pre>operator <i>unspecified-bool-type</i> () const; // never throws</pre> |
| <p>Returns an unspecified value that, when used in boolean contexts, is equivalent |
| to <code>get() != 0</code>.</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<class 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> |
| <hr> |
| <p>Revised <!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B %Y" startspan--> |
| 09 January 2003<!--webbot bot="Timestamp" endspan i-checksum="32310"--></p> |
| <p><small>Copyright 1999 Greg Colvin and Beman Dawes. Copyright 2002 Darin Adler. |
| Copyright 2002-2005 Peter Dimov. Distributed under the Boost Software License, Version |
| 1.0. See accompanying file <A href="../../LICENSE_1_0.txt">LICENSE_1_0.txt</A> or |
| copy at <A href="http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</A>.</small></p> |
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