atomic variable c
#include <stdio.h>
#include <threads.h>
#include <stdatomic.h>
atomic_int acnt;
int cnt;
int f(void* thr_data)
{
(void)thr_data;
for(int n = 0; n < 1000; ++n) {
++cnt;
++acnt;
// for this example, relaxed memory order is sufficient, e.g.
// atomic_fetch_add_explicit(&acnt, 1, memory_order_relaxed);
}
return 0;
}
int main(void)
{
thrd_t thr[10];
for(int n = 0; n < 10; ++n)
thrd_create(&thr[n], f, NULL);
for(int n = 0; n < 10; ++n)
thrd_join(thr[n], NULL);
printf("The atomic counter is %un", acnt);
printf("The non-atomic counter is %un", cnt);
}