條件變數：[單生產者/單消費者]單鏈表的插入和刪除

  typedef struct node{//宣告連結串列型別                                                                       
    int data;                                                                                                                    
    struct node* next;                                                                                                           
  }LNode;                                                                                                                        
                                                                                                                                 
  LNode* head=NULL; //臨界資源：連結串列的頭節點                                                                                             
                                                                                                                                 
  pthread_mutex_t mutex;                                                                                                         
  pthread_cond_t cond;                                                                                                           
                                                                                                                                 
  void* producer(void* arg){                                                                                                     
    while(1){                                                                                                                    
      LNode* node=(LNode*)malloc(sizeof(LNode)); //建立新的節點node                                                                              
      node->data=rand()%100;                                                                                                     
                                                                                                                                 
      pthread_mutex_lock(&mutex);                                                                                                
                                                                                                                                 
      node->next=head; //將node採用頭插法插入連結串列                                                                                          
      head=node;                                                                                                                 
      printf("           produce node=%d\n",node->data);                                                                         
                                                                                                                                 
      pthread_mutex_unlock(&mutex);                                                                                              
                                                                                                                                 
      sleep(rand()%3);                                                                                                           
  
      pthread_cond_signal(&cond); //插入node後，喚醒等待的執行緒去消費連結串列
    }
    return NULL;
  }
  void* customer(void* arg){                                                                                                     
    while(1){                                                                                                                    
      pthread_mutex_lock(&mutex);                                                                                                
      while(head==NULL){ //if(head==NULL)  如果連結串列為NULL，則一直阻塞
        pthread_cond_wait(&cond,&mutex);                                                                                         
      }                                                                                                                          
	  //採用頭刪法刪除節點
      LNode* delNode=head;                                                                                                       
      head=head->next;  //delete head                                                                                            
      printf("delete node=%d\n",delNode->data);                                                                                  
      free(delNode);                                                                                                             
                                                                                                                                 
      pthread_mutex_unlock(&mutex);                                                                                              
                                                                                                                                 
      sleep(rand()%3);                                                                                                           
    }                                                                                                                            
    return NULL;                                                                                                                 
  }                                                                                                                              
  int main(){                                                                                                                    
    pthread_mutex_init(&mutex,NULL);                                                                                             
    pthread_cond_init(&cond,NULL);                                                                                                                        
                                                                                                                                 
    pthread_t tid1,tid2;                                                                                                         
                                                                                                                                 
    pthread_create(&tid1,NULL,producer,NULL);                                                                                    
    pthread_create(&tid2,NULL,customer,NULL);                                                                                    
                                                                                                                                 
    pthread_join(tid1,NULL);         
    pthread_join(tid2,NULL);
                                                                                                                                 
    pthread_mutex_destroy(&mutex);
    pthread_cond_destroy(&cond);                                                                                                                  
                                                                                                                                 
    return 0;                                                                                                                    
  }