<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>scoped_array</title> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> </head> <body bgcolor="#ffffff" text="#000000"> <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> </body> </html>