Not only are uninitialized variables a frequent cause of bugs, but this kind of bug is particularly serious because it may not be reproducible; in some cases, programs with uninitialized variables may even pass software tests.
Not only are uninitialized variables a frequent cause of bugs, but this kind of bug is particularly serious because it may not be reproducible: for instance, a variable may remain uninitialised only in some branch of the program. In some cases, programs with uninitialized variables may even pass software tests.