Summary - Modern C
- C course
- Expert
- Lesson 30/47
- 5 min
Combine _Generic, _Static_assert and atomics to write a type-safe macro.
Summary - Modern C combined
In this lesson you'll combine _Generic, _Static_assert and atomics to write a type-safe macro. The safe_print macro uses _Generic to select the type, _Static_assert to verify int size, and an atomic_int counter to track calls.
Together these three features show the power of modern C: compile-time safety, type-based selection and thread-safe counting. You'll merge solutions from previous lessons into one program. The program prints the type name on each call and increments the counter; finally it prints the counter value.
Practice Write the safe_print macro
Add #include <stdatomic.h>. Write _Static_assert(sizeof(int) >= 4, "int en az 4 bayt");. Declare static atomic_int call_count = 0;. Write #define safe_print(x): select the type with _Generic((x), int: "int", double: "double", default: "diğer"), print via printf("%s\n", ...), then increment with atomic_fetch_add(&call_count, 1). In int main(void) call safe_print(42) and safe_print(3.14), finally print printf("%d\n", call_count).
Starter code
#include <stdio.h>
#include <stdatomic.h>
// derleme denetimi ekle
// atomik sayaç tanımla
// safe_print makrosunu yaz
// main'de çağır ve sayacı yazdırSample solution
#include <stdio.h>
#include <stdatomic.h>
_Static_assert(sizeof(int) >= 4, "int en az 4 bayt");
static atomic_int call_count = 0;
#define safe_print(x) printf("%s\n", _Generic((x), int: "int", double: "double", default: "diğer")); atomic_fetch_add(&call_count, 1)
int main(void) {
safe_print(42);
safe_print(3.14);
printf("%d\n", call_count);
return 0;
}Expected output
int double 2
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Which three features does safe_print combine?
- malloc, free, realloc
- _Generic, _Static_assert, atomics Correct answer
- printf, scanf, fprintf
- fork, exec, wait
Explanation: safe_print combines _Generic + _Static_assert + atomics.
2 Complete the atomic increment call
static atomic_int call_count = 0;
____(&call_count, 1);static atomic_int call_count = 0;
atomic_fetch_add(&call_count, 1);Explanation: atomic_fetch_add(&call_count, 1) atomically increments the counter.
3 Match feature to role
| Term | Meaning |
|---|---|
_Generic |
Type selection |
_Static_assert |
Compile check |
atomic_int |
Atomic counter |
printf |
Output writing |