How are variables tied to their values in C?

Question

If you have a line of code like

int num = 4;

Does this result in the following tables?

VARIABLE|ADDRESS   ADDRESS|VALUE
num     |0001      0001   |4

If you were to then say

int* num_p = #

Would this result in the following tables?

VARIABLE|ADDRESS   ADDRESS|VALUE
num     |0001      0001   |4
num_p   |0002      0002   |0001

Would then saying

int** num_pp = &num_p;

Result in the following tables?

VARIABLE|ADDRESS   ADDRESS|VALUE
num     |0001      0001   |4
num_p   |0002      0002   |0001
num_pp  |0003      0003   |0002

And so on? If so, would this same logic hold true if the initial variable were not an int but instead a struct?

EDIT: Check the comments on this question for info on what the addresses would actually look like as opposed to this made up 0001, 0002, 0003 scheme.

EDIT 2: This answer to this question points out the fact that variables do not necessarily have to have an address. This answer to an earlier question also goes into this.

Answer 1

Yes, what you illustrate with your tables is roughly correct. Variable names are assigned to addresses at compile time. This is called a "symbol table" and is analogous to the left-hand tables in your question. When the program runs, the variable names no longer appear in the executable and there are only addresses like you have in your tables on the right.

If so, would this same logic hold true if the initial variable were not an int but instead a struct?

Yes, a struct is a value, so assigning an address to a variable and a value to that address works the same way. The difference is that a struct might take more memory than an int depending on its members. This affects what address is available for the next variable.

Note that the addresses assigned will be offsets from some base memory address. When the OS loads the executable, it gives this base address and the executable calculates the absolute memory addresses by adding the offsets to the base address.

If you are interested in learning more about how this works, you can study compilers and operating systems in more detail.

Answer 2

would this same logic hold true if the initial variable were not an int but instead a struct?

A structure is a type (like int, double, char ...) not a variable, so yes, what you described will apply as well.