当前位置：首页 > news >正文

IO--进程实操

news 2025/7/3 10:40:48

1.创建一个进程扇

#include <051head.h>
int main(int argc, const char *argv[])
{pid_t pid;for(int i=0;i<4;i++){pid=fork();if(pid==-1) //父进程{ERRLOG("fork error..\n");}   else if(pid==0)  //这是子进程{                                                   printf("pid=%d  ppid=%d\n",getpid(),getppid());break；}//父进程//不用写代码，默认执行循环，继续进行fork}while(1);    //子进程while(waitpid(-1,NULL,WNOHANG)<=0); // 子进程结束，再回收return 0;
}

2.创建一个进程链

#include <25051head.h>
int main(int argc, const char *argv[])
{pid_t pid；for(int i=1;i<5;i++){pid=fork();if(pid==-1)  //这是子进程{ERRLOG("fork error\n");     }else if(pid>0) //父进程 {wait(NULL);     //阻塞   接受子进程资源  exit(0);                                            }//子进程//不用写，默认执行循环，继续forkprintf("pid=%d  ppid=%d\n",getpid(),getppid());}while(1);return 0;
}

3.请问打印的结果是什么

输出结果：

info1 from child process_2
info1 from child process_1
info1 from parent process
info2 from parent process

4.实现文件的拷贝，父进程拷贝前一部分，子进程拷贝后一部分

#include <25051head.h>
int main(int argc, const char *argv[])
{FILE* fp=fopen("my.txt","r");if(NULL==fp){ERRLOG("fopen error..\n");}fseek(fp,0,SEEK_END);int num=ftell(fp);int n=(num-1)/2;FILE* fd=fopen("my1.txt","w+");if(NULL==fd){ERRLOG("fopen error..\n");                              }char buf[128]="";pid_t pid=fork();if(0>pid){ERRLOG("fork error");}else if(0<pid){wait(NULL);   // 等待子进程完成fseek(fp,0,SEEK_SET);fseek(fd,0,SEEK_SET);while(n>0){size_t res=fread(buf,1,(n<sizeof(buf))? n:sizeof(buf),fp);if(res<=0){break;}fwrite(buf,1,n,fd);n-=res;}}else{fseek(fp,n,SEEK_SET);fseek(fd,0,SEEK_SET);while(n>0){size_t res=fread(buf,1,(n<sizeof(buf))? n:sizeof(buf),fp);if(res<=0){break;}fwrite(buf,1,n,fd);n-=res;exit(0);}}fclose(fp);fclose(fd);return 0;
}

打印结果：