实在不好意思，第一个版本有些问题，是局部变量和堆里面变量的区别。今天做了一下修改。代码如下。

#ifndef _LIST_H_
#define _LIST_H_
#include <string.h>
#include <stdio.h>
#include <stdlib.h>

struct List
{
	char * buffer;
	char * cursor;
	char * begin;
	char * end;
	
};
// you must add struct, otherwise it will prompt "expected ‘)’ before ‘*’ token"
void init(struct List * p_list);
int get_buffer_length (struct List * p_list);
void put_into_buffer(struct List* p_list,char *pc_char);
char get_from_buffer(struct List* p_list);


#endif

?

?? 主要是更改了结构体List的定义，buffer必须定义为堆里面的变量。

???#include "list.h"

void init(struct List * p_list){
	
	char *temp=(char *)malloc(10);
	memset(temp,'\0',10);
	p_list->buffer=temp;	
	p_list->cursor=(p_list->buffer)+10;
	p_list->begin=p_list->buffer;
	p_list->end=(p_list->buffer)+10;
	
	
}
int get_buffer_length(struct List * p_list){
	
	return p_list->end-p_list->cursor;
}

void put_into_buffer(struct List * p_list,char * pc_char){
		
	printf("put ........  %c\n",*pc_char);
	if(p_list->cursor<=p_list->begin||p_list->cursor>p_list->end)
		printf(" put error\n");
	//put the char into cursor's former place
	(p_list->cursor)--;
	memset(p_list->cursor,(int)(*pc_char),1);
		
}

char get_from_buffer(struct List * p_list){
	if(p_list->cursor<p_list->begin||p_list->cursor>p_list->end)
		printf(" get error\n");
   
    int length=get_buffer_length(p_list);
    printf("list length now is %d\n",length);
    (p_list->cursor)++;
    char result=*(p_list->end-1);
    printf("get ------------------- %c\n",result);
    
    if(length==1)
    {
 	
    	return result;
    }
   else
   	{
   		char *temp=(char *)malloc(10);
		bcopy(p_list->cursor-1,temp+10-length+1,length-1);
		free(p_list->buffer);
		p_list->buffer=temp;
		p_list->begin=temp;
		p_list->end=temp+10;
		p_list->cursor=p_list->end-length+1;   		
   	}

	return 0;
}

?

?? ?#include <pthread.h>

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include "List.h"

pthread_cond_t has_product = PTHREAD_COND_INITIALIZER;
pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;

//define the Producer thread
void * produce(void * arg)
{
	//arg is a char * pointer
	struct List * p_list=(struct List *)arg;
	//if buffer length =10,than wait,because buffer is full,
	
	while(1)
	{
		pthread_mutex_lock(&lock);  //正确位置，
		//printf("111111\n");
		if(get_buffer_length(p_list)==10)
		{
			//printf("22222222\n");
			int num1=pthread_cond_wait(&has_product, &lock);
			//printf("33333333\n");
			//printf(" num11111 %d\n",num1);
				
		}
		//buffer'length !=10,not full, we can put char into buffer.
		//printf("444444\n");
		//pthread_mutex_lock(&lock); //错误位置
		//printf("555555\n");
		char zifu=(char)(1+(int)(128.0*rand()/(RAND_MAX+1.0)));
		put_into_buffer(p_list,&zifu);
		//after put, if the length>0,we can notify the wait thread,means that you can get char now
		if(get_buffer_length(p_list)==1)
		{
			pthread_cond_signal(&has_product);	
			//printf("66666\n");
		}
		//printf("777777777777\n");
		int num3=pthread_mutex_unlock(&lock);
		//printf("unlocknumber  1111111111111 is %d\n",num3);
		//printf("888888888888\n");
		sleep(1);
	    //printf("99999999\n");
   }
	
}

//define the second thread
void * comsume(void * arg)
{	
	//arg is a char * pointer
	struct List * p_list=(struct List *)arg;
	while(1)
	{
		//if buffer length =10,than wait,because buffer is full,
		pthread_mutex_lock(&lock);  //正确位置，
		//printf("aaaaaaaaaa\n");
		if(get_buffer_length(p_list)==0)
		{
			//printf("bbbbbbbbbbbbbb\n");
			int num2=pthread_cond_wait(&has_product, &lock);
			//printf("cccccccccc