waitpid1.c

嵌入式Linux程序设计与应用案例 电子书源码 中国电力出版社

/***************
//  name : waitpid1.c
//  author : pyy
//  date : 2007-11-22
************/

#include<unistd.h>
#include<stdio.h>
#include<stdlib.h>
#include<sys/wait.h>
#include<sys/types.h>

void disp0();
void disp1();
void disp2();

int mymax(int ,int );
int main()
{
    pid_t child;
    int status,ans;
    void (*fun[3])();
    int (*pm)(int x, int y);
    int num1,num2,num3,max_num;
    fun[0] = disp0;
    fun[1] = disp1;
    fun[2] = disp2;
   
    pm = mymax;
    printf("copy ? yes or no: 1: yes 2: no "); 
    scanf("%d", &ans);
    if (ans ==1 )
    {
        child = fork(); //copy process
        if(child == -1)
        {
            perror("fork error"); exit(1);
        }
    }

     /* child process*/
    if( child == 0) 
    {
        puts("this is child process ... ");
        printf("\t child process pid = %d\n",getpid());
        printf("\t child process ppid =%d\n",getppid());
        printf("which one do you want? (0: computer 1 : tv 2 : video$)");
        scanf("%d",&num3);
        if(num3 >=0 && num3<=2) (*fun[num3])();  
        exit(0);
    }
    else 
    {
        waitpid(child,&status,0);
        puts("This is father process ....");
	printf("\t father pid =%d \n",getpid());
        printf("\t father ppid=%d \n",getppid());
        printf("\t child go :%d\n",WIFEXITED(status));
        printf("input first num: ");
        scanf("%d",&num1);
        printf("input second num: ");
        scanf("%d",&num2);
        max_num=(*pm)(num1,num2);
        printf("max is %d\n",max_num);
        exit(0);
    }
   
}

int mymax(int x, int y)
{
    if(x > y) return x; else return y;
}

void disp0()
{
    printf(" you want computer.\n");
}

void disp1()
{
    printf(" you want TV.\n");
}


void disp2()
{
    printf(" you want video$.\n");
}