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实验二结果二.txt

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+
+#include <stdio.h>   
+#include <stdlib.h>   
+#include <pthread.h>   
+#include <unistd.h>   
+#include <sys/types.h>   
+#include <semaphore.h> 
+sem_t count1,count2,count3; 
+void* p1(void *arg){
+	for(int i=0;i<30;i++){
+	sem_wait(&count1);
+	printf("A\n");
+	if(i % 3 == 2){
+	for(int i = 0;i < 3;i ++)
+    sem_post(&count2);
+	}
+	}
+} 
+void* p2(void *arg){
+	for(int i=0;i<30;i++){
+    sem_wait(&count2);
+	printf("B\n");
+	if(i % 3 == 2){
+	for(int i = 0;i < 3;i ++)
+    sem_post(&count3);
+	}
+	}
+} 
+void* p3(void *arg){
+	for(int i=0;i<30;i++){
+    sem_wait(&count3);
+	printf("C\n");
+	if(i % 3 == 2){
+	for(int i = 0;i < 3;i ++)
+    sem_post(&count1);
+	}
+	}
+} 
+
+int main()  
+{  
+    sem_init(&count1, 0 ,  3);
+    sem_init(&count2, 0 ,  0); 
+    sem_init(&count3, 0 ,  0);  
+	pthread_t tid[3];  
+	pthread_create(&tid[0], NULL, p1, NULL);  
+	pthread_create(&tid[1], NULL, p2, NULL);  
+	pthread_create(&tid[2], NULL, p3, NULL);  
+	for(int i = 0; i < 3; i++)  
+		pthread_join(tid[i], NULL);      
+	printf("main is over\n");
+}