Dears, Please advice output file not generated for this code

#include #include #include #include #include #include #include #include

/*This implementation uses POSIX threads to create three threads for the Alpha.exe, Counter.exe and Re.exe processes.*/

#define MAX_LEN 20 #define RE_EXEC_DELAY 1

pthread_mutex_t mutex; int counter = 0; char last_alpha_char; int last_counter;

void sig_handler(int sig) { printf("test"); pthread_mutex_lock(&mutex); FILE *fp = fopen("output.txt", "a"); if (!fp) perror("fopen");

if (fp == NULL) { printf("Error opening file! "); exit(1); } fprintf(fp, "Counter: %d Alpha: %c ", last_counter, last_alpha_char); fclose(fp); pthread_mutex_unlock(&mutex); }

void *alpha_func(void *arg) { while (1) { sleep(1); char random_char = 'A' + (rand() % 26); last_alpha_char = random_char; printf("%c ", random_char); } }

void *counter_func(void *arg) { while (1) { sleep(1); counter++; last_counter = counter; printf("%d ", counter); } }

void *re_func(void *arg) { while (1) { sleep(RE_EXEC_DELAY * 60); printf("RESTART "); } }

int main(int argc, char *argv[]) { signal(SIGTERM, sig_handler); /*Abnormal termination of the program, such as a call to abort.*/ signal(SIGINT, sig_handler); /*Receipt of an interactive attention signal.*/ srand(time(NULL));

pthread_t alpha, counter, re; pthread_create(&alpha, NULL, alpha_func, NULL); pthread_create(&counter, NULL, counter_func, NULL); pthread_create(&re, NULL, re_func, NULL);

pthread_join(alpha, NULL); pthread_join(counter, NULL); pthread_join(re, NULL);

return 0; }