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<concept id="GUID-011D0974-CC37-5335-A8EB-7ECF4FC30F93" xml:lang="en"><title>Cleanup
for heap arrays</title><shortdesc>C++ arrays are allocated on the heap and require their own particular
cleanup.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
<p>C++ arrays are allocated on the heap using <codeph>operator new[]</codeph>.
The cleanup rules for such arrays are as follows:</p>
<ul>
<li id="GUID-41AA28AA-1D48-5B50-9065-A283CCAAD83F"><p>if it is not necessary
to protect against leaves, such as when the array is a class member, or no
leaves can occur in the lifetime of the array, then always delete the array
using <codeph>operator delete[]</codeph> (not <codeph>operator delete</codeph>).</p> </li>
<li id="GUID-B4EA79E7-EEDC-531D-90DB-7041F3650356"><p>if it is necessary to
protect against leaves, push the array to the cleanup stack using the utility
template function <codeph>CleanupArrayDeletePushL()</codeph>. This ensures
that if a leave occurs, the array is deleted correctly using <codeph>operator
delete[]</codeph>.</p> <p>Arrays should <i>not</i> be pushed to the cleanup
stack using the standard <codeph>CleanupStack::PushL()</codeph>, as this will
result in <codeph>operator delete</codeph> rather than <codeph>operator delete[]</codeph> being
used for cleanup.</p> </li>
</ul>
<p><b>Note on compiler behaviour</b> </p>
<p>Of the compilers used with Symbian platform, Metrowerks CodeWarrior is
the most sensitive to the rules for array deletion. If an array is deleted
with a simple <codeph>delete</codeph> rather than <codeph>delete[]</codeph>,
then a USER 42 panic (invalid heap cell) can occur. </p>
<p>This panic in fact occurs for arrays in which the class has either a constructor
or a destructor. For such arrays, CodeWarrior reserves space at the start
of the array storage to hold the number of elements in the array: this means
the first heap cell is not the start of a deletable object. GCC and MSVC C++
only reserve such extra space if the class has a destructor.</p>
</conbody></concept>