From 332a45e905a7355cfc17ddae7c29eb26bd42c191 Mon Sep 17 00:00:00 2001
From: TomatenMarc <marc.feger@uni-duesseldorf.de>
Date: Tue, 22 May 2018 22:10:29 +0200
Subject: [PATCH] Semaphoren
---
Semaphoren/semaphoren.c | 69 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 69 insertions(+)
create mode 100644 Semaphoren/semaphoren.c
diff --git a/Semaphoren/semaphoren.c b/Semaphoren/semaphoren.c
new file mode 100644
index 0000000..9ba55cb
--- /dev/null
+++ b/Semaphoren/semaphoren.c
@@ -0,0 +1,69 @@
+/* gcc sema_vorgabe.c -o sema_vorgabe -lpthread */
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <pthread.h>
+#include <semaphore.h>
+
+sem_t sem_1;
+sem_t sem_2;
+
+void *print_stern (void *dummy) {
+ char ch = '*';
+
+ while(1) {
+ sem_wait(&sem_1);
+ putchar(ch);
+ fflush(stdout);
+ sem_post(&sem_2);
+ }
+
+ return NULL;
+}
+
+void *print_minus (void *dummy) {
+ char ch = '-';
+
+ while(1) {
+ sem_wait(&sem_2);
+ putchar(ch);
+ fflush(stdout);
+ sem_post(&sem_1);
+ }
+
+ return NULL;
+}
+
+int main () {
+ pthread_t tref1, tref2;
+
+ if(sem_init(&sem_1, 0, 0)){
+ perror("sem_1 init fail");
+ return -1;
+ }
+ if(sem_init(&sem_2, 0, 1)){
+ perror("sem_2 init fail");
+ return -1;
+ }
+
+ if (pthread_create (&tref1, NULL, print_minus, NULL)) {
+ fprintf(stderr, "error: creating thread 1 failed.\n");
+ return EXIT_FAILURE;
+ }
+
+ if (pthread_create (&tref2, NULL, print_stern, NULL)) {
+ fprintf(stderr, "error: creating thread 2 failed.\n");
+ return EXIT_FAILURE;
+ }
+
+ if (pthread_join (tref1, NULL)) {
+ fprintf(stderr, "error: joining thread 1 failed.\n");
+ return EXIT_FAILURE;
+ }
+ if (pthread_join (tref2, NULL)) {
+ fprintf(stderr, "error: joining thread 2 failed.\n");
+ return EXIT_FAILURE;
+ }
+
+ return EXIT_SUCCESS;
+}
--
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