Showing posts with the label Uninitialized Variables

What Value Is Stored In Uninitialized Variables?

The value in an uninitialized variable is one of: zero, a compiler dependent value (such as 0xCC's in visual studio), or data previously stored in that memory location (old data). Types of Uninitialized Variables And Their Values Classic C/C++ Uninitialized Stack Variables The classic type of uninitialized variables are local function variables written in a low level language (such as C/C++). You would think when these variables are left uninitalized they would simply save the last value they were give. However, there is a catch: when code is compiled in debug mode, the compiler may inject its own code that initializes empty variables to a default value. This is done to protect against vulnerabilities (more on this later), and to more easily detect bugs by giving the variable a bogus value that can be easily identified as uninitialized if it is for example printed to the screen. Below, a  program compiled with Visual Studio in debug mode prints an uninitialized variable.