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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>