进程线程例子

fork()创建子进程

#include <unistd.h>#include <sys/types.h>#include <sys/wait.h>#include <stdio.h>#include <stdlib.h>#include <errno.h>#include <math.h>int main(void){       pid_t child;     /* 创建子进程 */    if((child=fork())==-1)    {       printf("Fork Error : %s\n", strerror(errno));       exit(1);       }       else        if(child==0) //子进程       {           printf("I am the child: %d\n", getpid());           exit(0);       }       else//父进程       {           printf("I am the father:%d\n",getpid());           return 0;           }}

fork()创建的子进程后，父子进程是同时、独立运行的，进程的空间是相互独立的，没有固定先后顺序。

jbc@jbc-virtual-machine# 45:~/work/guoqian/code1/2-2-1$ ./fork_pidI am the child: 3255I am the father:3254jbc@jbc-virtual-machine# 46:~/work/guoqian/code1/2-2-1$ ./fork_pidI am the father:3260I am the child: 3261

vfork()创建子进程

#include <stdio.h>#include <stdlib.h>#include <errno.h>#include <math.h>                int main(void)  {                   pid_t child;            /* 创建子进程 */    if((child=vfork())==-1)    {        printf("Fork Error : %s\n", strerror(errno));        exit(1);    }    else            if(child==0) // 子进程    {         sleep(1); //子进程睡眠一秒         printf("I am the child: %d\n", getpid());         exit(0);    }           else        //父进程    {                printf("I am the father:%d\n",getpid());         exit(0);    }   }

vfork()创建子进程后必定是子进程运行完才会运行父进程。

jbc@jbc-virtual-machine# 55:~/work/guoqian/code1/2-2-2$ ./a.out I am the child: 3504I am the father:3503jbc@jbc-virtual-machine# 56:~/work/guoqian/code1/2-2-2$ ./a.out I am the child: 3509I am the father:3508

创建线程

#include <stdio.h>#include <pthread.h>#include <unistd.h>#include <stdlib.h>struct menber {                 int a;        char *s;  };            /*线程执行函数*/void *create(void *arg){                 struct menber *temp;    temp=(struct menber *)arg;    printf("menber->a = %d  \n",temp->a);    printf("menber->s = %s  \n",temp->s);    return (void *)0;}             int main(int argc,char *argv[]){                 pthread_t tidp;    int error;    struct menber *b;    /*为结构体指针b分配内存并赋值*/    b=(struct menber *)malloc( sizeof(struct menber) );    b->a = 4;     b->s = "zieckey";    /*创建线程并运行线程执行函数*/    error = pthread_create(&tidp, NULL, create, (void *)b);    if( error )    {                                                                                                                                                       printf("phread is not created...\n");        return -1;    }             sleep(1); //进程睡眠一秒使线程执行完后进程才会结束    printf("pthread is created...\n");    return 0; }             

线程和任务（task）有点类似，使用pthread_create()创建线程后，线程为就绪态，运行结果：

jbc@jbc-virtual-machine# 64:~/work/guoqian/code1/2-5-1$ ./a.out menber->a = 4  menber->s = zieckey  pthread is created...

线程等待

#include <pthread.h>#include <unistd.h>#include <stdio.h>void *thread(void *str){             int i;    for (i = 0; i < 3; ++i)    {             sleep(2);        printf( "This in the thread : %d\n" , i );    }         return NULL;}         int main(){             pthread_t pth;    int i;                                                                                                                                              /*创建线程并执行线程执行函数*/    int ret = pthread_create(&pth, NULL, thread, NULL);    printf("The main process will be to run,but will be blocked soon\n");    /*阻塞等待线程退出*/    pthread_join(pth, NULL);    printf("thread was exit\n");    for (i = 0; i < 3; ++i)    {                         sleep(1);        printf( "This in the main : %d\n" , i );    }               return 0;}

pthread_join()将会阻塞当前进程直到线程退出,运行结果：

The main process will be to run,but will be blocked soonThis in the thread : 0This in the thread : 1This in the thread : 2thread was exitThis in the main : 0This in the main : 1This in the main : 2