Help with basic threading concept / race conditions

void *thread_main(void *thread_number) {
    printf("In thread number %d.n", *(int *)thread_number);
}

void main() {
    int i = 0;
    pthread_t thread;

    for( i = 0; i < 10; i++ ) {
        printf("Creating thread %d.n");
        pthread_create(&thread, 0, thread_main, &i);
        printf("Created thread %d.n");
    }
}

> Creating thread 1.
> In thread number 1.
> Created thread 1.
> Creating thread 2.
> In thread number 2.
> Created thread 2.

for( i = 0; i < 10; i++ ) {
    int *thread_count = malloc(sizeof(int));
    *thread_count = i;
    printf("Creating thread %d.n", i);
    pthread_create(&thread, 0, thread_main, thread_count);
    printf("Created thread %d.n", i);
}

void *thread_main(void *thread_number) {
    printf("In thread number %d.n", *(int *)thread_number);
    free(thread_numbr);
}