difference between stack segment and uninitialized data segment

Question

I was trying to get a hand over the memory allocation in c.

According to the following link, the stack and the uninitialized data segment are different and the uninitialized data of the local function goes to the uninitialized data segment.

If that is the case then what is stored in the stack segment in case of a code with uninitialized local variables? Is it empty?

Answer 1

I would not recommend reading "geeksforgeeks" tutorials. You have some misconceptions.

What they call "uninitialized data", the .bss segment, is in fact a store for variables of static storage duration that are zero-initialized. Including any such variable which is explicitly initialized to value zero. An explanation of static storage duration and the different common segments, with examples, can be found here.

Only variables with static storage duration end up in .bss and .data. Local variables always end up on the stack, or in CPU registers, no matter if they are initialized or not.

(Please note that none of this is specified by the ISO C standard, but rather by industry de facto standards.)

Answer 2

the uninitialized data of the local function goes to the uninitialized data segment.

Well, that is not entirely true.

Read carefully, (from the same link, emphasis mine)

[...] uninitialized data starts at the end of the data segment and contains all global variables and static variables that are initialized to zero or do not have explicit initialization in source code. [...]

So, the automatic storage variables still resides in stack segment, irrespective of the fact whether they are initialized or not.

That said, a word of caution, this is "A typical memory representation", not universal. C standard does not mandate to have a stack segment (or any other), for the matter.