[C++]多线程: 教你写第一个线程

来源：互联网发布：文字编辑软件编辑：程序博客网时间：2024/06/05 12:46

hello thread!

声明线程A的端口号
```
#include <pthread.h>pthread_t tid;
```

定义线程运行函数

void thread_function(void *args){    printf("thread_function is called!\n");    //注意区别 cout << "thread_function is called! << endl; 和上一行}

创建线程

pthread_create(&tid, NULL, &thread_function, NULL);

(optional)阻塞: 挂起当前线程，直到tid线程结束
```
pthread_join(tid, NULL);
```

好了，这样就可以启一个线程了，完整代码如下：

#include<unistd.h>#include<stdio.h>#include<cstring>#define MAX_THREAD 2pthread_t thread[MAX_THREAD];pthread_mutex_t mut;int num = 0;void* thread1(void *args){    printf("hi, I am thread1\n");    for(int i=0; i < 6; i++){        pthread_mutex_lock(&mut);        printf("[thread1]num=%d, i=%d\n", num, i);            num ++;        pthread_mutex_unlock(&mut);        sleep(2);    }    pthread_exit(NULL);}void* thread2(void *args){    printf("hi, I am thread2\n");    for(int i = 0; i < 10; i++)    {        pthread_mutex_lock(&mut);        printf("[thread2]num=%d, i=%d\n", num, i);            num ++;        pthread_mutex_unlock(&mut);        sleep(3);    }    pthread_exit(NULL);}void thread_create(){    memset(&thread, 0, sizeof(thread));    if( 0!=pthread_create(&thread[0], NULL, thread1, NULL))        printf("thread1 create faild\n");    else            printf("thread1 established\n");    if( 0 != pthread_create(&thread[1], NULL, thread2, NULL))        printf("thread2 create faild\n");    else        printf("thread2 established\n");}void thread_wait(){    if(0 != thread[0])    {        pthread_join(thread[0], NULL);        printf("thread 1 is over\n");    }    if(0 != thread[1])    {        pthread_join(thread[1], NULL);        printf("thread 2 is over\n");    }}int main(){    pthread_mutex_init(&mut, NULL);    printf("main thread: creating threads...\n");    thread_create();    printf("main thread: waiting threads to accomplish task...\n");    thread_wait();    return 0;}

代码，得到结果:

tmain thread: creating threads…
thread1 established
hi, I am thread1
[thread1]num=0, i=0
thread2 established
main thread: waiting threads to accomplish task…
hi, I am thread2
[thread2]num=1, i=0
[thread1]num=2, i=1
[thread2]num=3, i=1
[thread1]num=4, i=2
[thread2]num=5, i=2
[thread1]num=6, i=3
[thread1]num=7, i=4
[thread2]num=8, i=3
[thread1]num=9, i=5
[thread2]num=10, i=4
thread 1 is over
[thread2]num=11, i=5
[thread2]num=12, i=6
[thread2]num=13, i=7
[thread2]num=14, i=8
[thread2]num=15, i=9
thread 2 is over

OK，现在说一下pthread_create方法的原型

pthread_create方法

作用

创建线程

原型

```int pthread_create(pthread_t *restrict tidp,const pthread_attr_t *restrict_attr,void*（*start_rtn)(void*),void *restrict arg);```

参数

第一个参数是指向线程标识符的指针
第二个参数用来设置线程的属性
第三个参数是线程运行函数的首地址
第四个参数是线程运行函数的参数

返回值

若成功，则返回0；否则，返回错误编号。

pthread_join方法

这里写图片描述

作用

这个函数是一个线程阻塞的函数
等待线程结束再继续往下执行，要不然主进程和下面的线程并行执行

原型

extern int pthread_join __P ((pthread_t __th, void **__thread_return))

参数

第一个参数是被等待线程的标识符
第二个参数是用户自定义的指针。用来存储被等待线程的返回值

0 0