Linux基础(15)多线程编程

#include<pthread.h>
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
void *helloworld(char *argc);
int main(int argc,int argv[])
{
    int error;
    int *temptr;
    
    pthread_t thread_id;
    
    pthread_create(&thread_id,NULL,(void *)*helloworld,"helloworld");    //创建子线程
    printf("*p=%x,p=%x
",*helloworld,helloworld);
    if(error=pthread_join(thread_id,(void **)&temptr))                    //等待子线程退出,并接受返回的堆指针
    {
        perror("pthread_join");
        exit(EXIT_FAILURE);    
    }
    printf("temp=%x,*temp=%c
",temptr,*temptr);
    *temptr='d';                                                        //使用子线程创建的堆
    printf("%c
",*temptr);    
    free(temptr);                                                        //释放
    return 0;
}

void *helloworld(char *argc)
{
    int *p;
    p=(int *)malloc(10*sizeof(int));                                //子线程创建了一个堆
    printf("the message is %s
",argc);    
    printf("the child id is %u
",pthread_self());
    memset(p,'c',10);
    printf("p=%x
",p);
    pthread_exit(p);                                                //把堆的指针返回出去
    //return 0;
}

//this is the test code for pthread_key 

#include <stdio.h> 
#include <pthread.h> 

pthread_key_t key;                                             //线程私有类型的变量
void echomsg(void *t) 
{ 
    printf("destructor excuted in thread %u,param=%u
",pthread_self(),((int *)t)); 
} 

void * child1(void *arg) 
{ 
    int i=10;
    int tid=pthread_self(); 
    printf("
set key value %d in thread %u
",i,tid); 
    pthread_setspecific(key,&i);                                 //要使用特定的设置函数才能设置当前线程私有的变量
    printf("thread one sleep 2 until thread two finish
");
    sleep(2); 
    printf("
thread %u returns %d,add is %u
",tid,*((int *)pthread_getspecific(key)),(int *)pthread_getspecific(key)); 
} 

void * child2(void *arg) 
{ 
    int temp=20;
    int tid=pthread_self(); 
    printf("
set key value %d in thread %u
",temp,tid); 
    pthread_setspecific(key,&temp); 
    sleep(1); 
    printf("thread %u returns %d,add is %u
",tid,*((int *)pthread_getspecific(key)),(int *)pthread_getspecific(key)); 
} 

int main(void) 
{ 
    pthread_t tid1,tid2; 
    pthread_key_create(&key,echomsg);                 //创建线程私有的变量,每个线程都可以继承这个变量,但是内存地址不同而互不影响 ,在线程结束后会调用echomsg()
    pthread_create(&tid1,NULL,(void *)child1,NULL); 
    pthread_create(&tid2,NULL,(void *)child2,NULL); 
    pthread_join(tid1,NULL);
    pthread_join(tid2,NULL);
    pthread_key_delete(key);                         //删除线程私有变量
    return 0; 
} 

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <pthread.h>
#include <semaphore.h>
#include <string.h>

void *thread_function(void *arg);

pthread_mutex_t work_mutex;             //互斥锁

#define WORK_SIZE 1024
char work_area[WORK_SIZE];                //共享内存区域
int time_to_exit = 0;                    //是否退出的信号

int main(int argc,char *argv[]) 
{
    int res;
    pthread_t a_thread;
    void *thread_result;
    res = pthread_mutex_init(&work_mutex, NULL);         //初始化并创建锁对象
    if (res != 0) 
    {
        perror("Mutex initialization failed");
        exit(EXIT_FAILURE);
        }
        res = pthread_create(&a_thread, NULL, thread_function, NULL);        //创建线程
    if (res != 0) 
    {
        perror("Thread creation failed");
        exit(EXIT_FAILURE);
    }
    pthread_mutex_lock(&work_mutex);                                        //上锁
    printf("Input some text. Enter 'end' to finish
");
    while(!time_to_exit)                                                     //判断是否输入了end,如果为1则退出循环写                
    {
        fgets(work_area, WORK_SIZE, stdin);        //get a string from stdin    //往共享区域里写
        pthread_mutex_unlock(&work_mutex);        //unlock the mutex            //解锁
        while(1) 
        {
            pthread_mutex_lock(&work_mutex);                                //上锁
            if (work_area[0] != '