Comment by levodelellis

Would you accept a short answer? The 'short' answer is the compiler tracks various things such as memory owner (for alloc) and lifetime (for constructors/destructors). The compiler enforces rules so it's clear (to the compiler) if the memory owner belongs to the caller function (for example ReadEntireFile), the parent function (itoa causes the calling function to pass in a hidden buffer for it to use) and if it's on the stack, heap or belongs to an object (class struct or array)