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This might look like a smart way to assign the return value of <code>malloc</code> to <code>ptr</code> and check if it is <code>NULL</code> in one step, but the <code>malloc</code> call and the assignment to <code>ptr</code> is a side effect of evaluating the expression that forms the <code>assert</code> condition. When the <code>NDEBUG</code> parameter is passed to the compiler, as when the program is considered to be error-free and released, the <code>assert()</code> statement is removed, so <code>malloc()</code> isn't called, rendering <code>ptr</code> uninitialised. This could potentially result in a [[segmentation fault]] or similar [[null pointer]] error much further down the line in program execution, causing bugs that may be [[Heisenbug|sporadic]] and/or difficult to track down. Programmers sometimes use a similar VERIFY(X) define to alleviate this problem.
Modern compilers may issue a warning when encountering the above code.<ref>{{Cite web|url=https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wparentheses-367|title=Warning Options (Using the GNU Compiler Collection (GCC))}}</ref>
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