完成并修改正确必做题

exp1/task62.c

@@ -5,51 +5,29 @@
 #include <unistd.h>
 #include <semaphore.h>
 
+void *increase(void *vargp);
+void *decrease(void *vargp);
 int cnt = 0;
 sem_t mutex;
 
-void *increase(void *vargp)
-{
-    unsigned int niters = (unsigned int)vargp;
-    for (unsigned int i = 0; i < niters; i++)
-    {
-        sem_wait(&mutex);
-        cnt++;
-        sem_post(&mutex);
-    }
-    return NULL;
-}
-
-void *decrease(void *vargp)
-{
-    unsigned int niters = (unsigned int)vargp;
-    for (unsigned int i = 0; i < niters; i++)
-    {
-        sem_wait(&mutex);
-        cnt--;
-        sem_post(&mutex);
-    }
-    return NULL;
-}
-
 int main(int argc, char **argv)
 {
     unsigned int niters;
     pthread_t t1,t2;
-
+    
     if (argc != 2)
     {
         printf("Usage: %s <niters>\n", argv[0]);
         exit(2);
     }
     niters = atoll(argv[1]);
-
+    
     sem_init(&mutex, 0, 1);
-    pthread_create(&t1,NULL,increase,(void*)niters);
-    pthread_create(&t2,NULL,decrease,(void*)niters);
+    pthread_create(&t1,NULL,increase,(void *)niters);
+    pthread_create(&t2,NULL,decrease,(void *)niters);
     pthread_join(t1,NULL);
     pthread_join(t2,NULL);
-
+    
     if (cnt != 0)
     {
         printf("Error! cnt=%d\n", cnt);
@@ -60,4 +38,28 @@ int main(int argc, char **argv)
     }
     sem_destroy(&mutex);
     exit(0);
+}
+
+void *increase(void *vargp)
+{
+    unsigned i ,niters = (unsigned int)vargp;
+    for ( i = 0; i < niters; i++)
+    {
+        sem_wait(&mutex);
+        cnt++;
+        sem_post(&mutex);
+    }
+    return NULL;
+}
+
+void *decrease(void *vargp)
+{
+    unsigned i, niters = (unsigned int)vargp;
+    for ( i = 0; i < niters; i++)
+    {
+        sem_wait(&mutex);
+        cnt--;
+        sem_post(&mutex);
+    }
+    return NULL;
 }