多线程

以下两个程序交替运行，编译时gcc -o thread1 thread1.c -lpthread ，如果需要传入一个参数，只需要在创建线程时把第四个参数改为传入的参数就可以了，NULL改为null不能编译通过，pthread_join使一个线程等待另一个线程结束,因为sleep所以运行一秒就停下等待另一个线程运行结束，第二个参数是用来存储等待线程返回值

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

void *mythread1(void)  
{  
    int i;  
    for(i = 0; i < 10; i++)  
    {  
        printf("This is the 1st pthread,created by xiaoqiang!
");  
        sleep(1);  
    }  
}  

void *mythread2(void)  
{  
    int i;  
    for(i = 0; i < 10; i++)  
    {  
        printf("This is the 2st pthread,created by xiaoqiang!
");  
        sleep(1);  
    }  
}  

int main(int argc, const char *argv[])  
{  
    int i = 0;  
    int ret = 0;  
    pthread_t id1,id2;  

    ret = pthread_create(&id1, NULL, (void *)mythread1,NULL);  //注意创建成功返回0值
    if(ret)  
    {  
        printf("Create pthread error!
");  
        return 1;  
    }  

    ret = pthread_create(&id2, NULL, (void *)mythread2,NULL);  
    if(ret)  
    {  
        printf("Create pthread error!
");  
        return 1;  
    }  

    pthread_join(id1,NULL);  
    pthread_join(id2,NULL);  

    return 0;  
}  

下面这个程序例子是使用多个线程输出100到1，思路是使用线程锁，保证每次只有一个线程在运行

#include<stdio.h>
#include<pthread.h>
pthread_mutex_t mut;//定义锁
pthread_t thread[4];
int n=100;
void *thread1(){
    while(n>0){
    pthread_mutex_lock(&mut);//锁起
    printf("this is thread1 n is %d
",n--);
    pthread_mutex_unlock(&mut);//解锁
    sleep(1);
    }
}
void *thread2(){
    while(n>0){
    pthread_mutex_lock(&mut);
    printf("this is thread2 n is %d
",n--);
    pthread_mutex_unlock(&mut);
    sleep(1);
    }
}
void *thread3(){
    while(n>0){
    pthread_mutex_lock(&mut);
    printf("this is thread3 n is %d
",n--);
    pthread_mutex_unlock(&mut);
    sleep(1);
    }
}
void *thread4(){
    while(n>0){
    pthread_mutex_lock(&mut);
    printf("this is thread4 n is %d
",n--);
    pthread_mutex_unlock(&mut);
    sleep(1);
    }
}

int main(){
    pthread_mutex_init(&mut,NULL);//初始化锁
    pthread_create(&thread[0],NULL,thread1,NULL);
    pthread_create(&thread[1],NULL,thread2,NULL);
    pthread_create(&thread[2],NULL,thread3,NULL);
    pthread_create(&thread[3],NULL,thread4,NULL);
    pthread_join(thread[0],NULL);
    pthread_join(thread[1],NULL);
    pthread_join(thread[2],NULL);
    pthread_join(thread[3],NULL);
return 0;}