pkutaj

#include <stdio.h>

void my_func() {
  int local_var = 42;
  printf("code address of my_func: %p\n", (void*)my_func);
  printf("stack address of local_var: %p\n", (void*)&local_var);
}

my_func()

pkutaj

[cling]$ my_func()
code address of my_func: 0x109cd0000
stack address of local_var: 0x16b625f9c

pkutaj

High addresses
┌──────────────┐
│    Stack     │  ← &local_var lives here (grows ↓)
├──────────────┤
│   (unused)   │
├──────────────┤
│    Heap      │  ← malloc'd memory (grows ↑)
├──────────────┤
│    .bss      │  ← uninitialized globals
├──────────────┤

pkutaj

typedef union AgeOrName {
  int age;
  const char *name;
} age_or_name_t;

pkutaj

#include <stdio.h>
typedef enum { OK = 200, NOT_FOUND = 404 } status_t;
status_t s = NOT_FOUND;
printf("status: %d\n", s); // 404 (C enums have no built-in way to print the label)

pkutaj

typedef union lucky_value {int n; const char *s;} lucky_t;
lucky_t pavol_luckies = {.n = 42};
printf("Pavol's lucky  value: %s\n'", pavol_luckies.s);

pkutaj

[cling]$ printf("Pavol's lucky  value: %s\n'", pavol_luckies.s);
Stack dump without symbol names (ensure you have llvm-symbolizer in your PATH or set the envi
ronment var `LLVM_SYMBOLIZER_PATH` to point to it):
...
0.      Program arguments: /opt/homebrew/Cellar/cling/1.2_1/libexec/bin/cling
Segmentation fault: 11

pkutaj

#include <stdio.h>
age_or_name_t pavol = { .age = 42 };
printf("age: %d\n", pavol.age);

pkutaj

printf("name: %s\n", pavol.name);

pkutaj

❯ cling
ERROR in cling::CIFactory::createCI():
  resource directory /private/tmp/cling-20251104-5233-k3pv11/cling-1.2/build/lib/clang/18 not
 found!

****************** CLING ******************
* Type C++ code and press enter to run it *
*             Type .q to exit             *
*******************************************
[cling]$ printf("name: %s\n", pavol.name);