Question

请教linux下c语言函数fork父进程打印子进程的PID

用于输入：n （在父进程中输入）
输出：从1到n的整数（子进程负责打印）
父进程打印子进程的PID，然后等待子进程结束，最后输出child complete，退出系统

Answer 1

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

int main()
{
int pipe_fds[2];
int pid;
if(pipe(pipe_fds))
{
fprintf(stderr,"pipe error!\n");
return -1;
}
if((pid = fork())<0)
{
fprintf(stderr, "fork error!\n");
return -1;
}
if(pid == 0)
{
char buf[20] = {0};
int n,i;
close(pipe_fds[1]);
read(pipe_fds[0],buf,sizeof(buf));
n=atoi(buf);
for(i=1;i<=n;i++)
{
if(i%10 == 0)
printf("\n");
printf("%d\t",i);
}
close(pipe_fds[0]);
}
else
{
int m;
char bf[20] = {0};
close(pipe_fds[0]);
printf("the child pid:%d\n",pid);
printf("please input number:");
scanf("%d",&m);
printf("\n");
sprintf(bf,"%d",m);
write(pipe_fds[1],bf,sizeof(bf));
wait(NULL);
printf("child complete!\n");
}
return 0;
}