This rule finds calls to functions that use a global variable before the variable has been initialized. Not all compilers generate code that zero-out memory, especially when optimizations are enabled or the compiler is not compliant with the latest language standards. Accessing uninitialized memory will lead to undefined results.

Initialize the global variable. If no constant can be used for initialization, ensure that all accesses to the variable occur after the initialization code is executed.

In the example below, callCtr is wrongly used before it has been initialized.

SEI CERT C++ Coding Standard: EXP53-CPP. Do not read uninitialized memory.