What does “Memory allocated at compile time” really mean?

Question

In programming languages like C and C++, people often refer to static and dynamic memory allocation. I understand the concept but the phrase \"All memory was allocated (rese

Answer 1

Memory allocated at compile time simply means there will be no further allocation at run time -- no calls to malloc, new, or other dynamic allocation methods. You'll have a fixed amount of memory usage even if you don't need all of that memory all of the time.

Isn't memory allocation by definition a runtime concept?

The memory is not in use prior to run time, but immediately prior to execution starting its allocation is handled by the system.

If I make a 1KB statically allocated variable in my C/C++ code, will that increase the size of the executable by the same amount?

Simply declaring the static will not increase the size of your executable more than a few bytes. Declaring it with an initial value that is non-zero will (in order to hold that initial value). Rather, the linker simply adds this 1KB amount to the memory requirement that the system's loader creates for you immediately prior to execution.