用C语言编写程序建立一个pipe
1、用C语言编写程序，建立一个pipe, 同时父进程生成一个子进程，子进程向pipe写入一
个字符串”Hello.”，父进程从pipe中读取该字符串。5'
#include
#include
#include
#include
#include
#include
int main()
{
char buf[20];
int piledes[2];
pid_t pid;
int ret;
if(ret = pipe(piledes) == -1)
{
perror("error on pipe:");
exit(-1);
}
else
{
pid = fork();
if(pid < 0)
{
perror("error on fork:");
exit(-1);
}
else if(pid == 0)
{
close(piledes[0]);
printf("to fu:");
fgets(buf,sizeof(buf)-1,stdin);
if((ret = write(piledes[1],buf,strlen(buf))) < 0)
{
perror("error on writing:");
exit(-1);
}
close(piledes[1]);
}
else
{
close(piledes[1]);
if((ret = read(piledes[0],buf,sizeof(buf)-1)) < 0)
{
perror("error on reading:");
exit(-1);
}
buf[ret] = '\0';
printf("from zi:%s\n",buf);
close(piledes[0]);
}
}
return 0;
}
2、编写一个 C语言程序lswc，使之功能能和ls | wc 等价。(也就是利用，fork,exec,以及ls,wc，以及重定向，或者是管道的系统调用) 13’
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
int main(int argc,char *argv[])
{
int pildes[2];
int ret;
char *argument[3];
pid_t pid;
char buf[1000];
if(argc < 2)
{
printf("que shao can shu\n");
exit(0);
}
argument[0] = "ls";
argument[1] = "/";
argument[2] = NULL;
if((ret = pipe(pildes)) < 0)
{
perror("error on pipe:");
exit(-1);
}
pid = fork();
if(pid <0)
{
printf("fork error\n");
exit(-1);
}
if(pid == 0)
{
close(pildes[0]);
dup2(pildes[1],1);
execvp("ls",argument);
close(pildes[1]);
}
else
{
close(pildes[1]);
// dup2(fildes[0],0);
if(strcmp((argv[1]),"wc") == 0)
{
bzero(buf,sizeof(buf));
if((ret = read(pildes[0],buf,sizeof(buf))) < 0)
{
printf("error on reading:");
exit(-1);
}
buf[ret] = '\0';
printf("%s",buf);
close(pildes[0]);
}
}
return 0;
}
3、实现一个具有头节点的链表。要求具有create, insert, delete, search功能，能对链表。
编写一个应用程序，使用上面的函数。 10'
#include
#include
#include
#include
#define PASSWD 111111
struct student
{
int num;
char name[20];
float grade;
struct student *next;
};
typedef struct student stuNode;
typedef struct student *stuPtr;
int stuwrite(stuPtr head)
{
FILE *fp;
fp = fopen("stu","w");
while(head->next != NULL)
{
head = head->next;
fwrite(head,sizeof(stuNode),1,fp);
}
close(fp);
return 0;
}
stuPtr sturead()
{
FILE *fp;
stuPtr head,p1,p2;
int a;
head = (stuPtr)malloc(sizeof(stuNode));
head->next = NULL;
p1 = head;
fp = fopen("stu","r");
do
{
p2 = (stuPtr)malloc(sizeof(stuNode));
p2->next = NULL;
a = fread(head,sizeof(stuNode),1,fp);
p1->next = p2;
p1 = p2;
}while(a == 1);
fclose(fp);
return head;
}
void creat()
{
stuPtr head,p;
head = (stuPtr)malloc(sizeof(stuNode));
p = (stuPtr)malloc(sizeof(stuNode));
p->next = NULL;
head->next = p;
printf("学号：");
scanf("%d",&(p->num));
getchar();
printf("姓名：");
scanf("%s",p->name);
getchar();
printf("成绩：");
scanf("%f",&(p->grade));
getchar();
stuwrite(head);
}
stuPtr insert(stuPtr head)
{
stuPtr p,q;
p = (stuPtr)malloc(sizeof(stuNode));
printf("学号：");
scanf("%d",&(p->num));
getchar();
printf("姓名：");
scanf("%s",p->name);
getchar();
printf("成绩：");
scanf("%f",&(p->grade));
getchar();
q = head;
while(q->next != NULL && p->num > q->next->num) {
q = q->next;
}
p->next = q->next;
q->next = p;
stuwrite(head);
p = sturead();
return p;
}
stuPtr search(stuPtr head,int num)
{
stuPtr p1,p2;
int flag;
p1 = (stuPtr)malloc(sizeof(stuNode));
p2 = (stuPtr)malloc(sizeof(stuNode));
p1 = head;
while(p1->next != NULL)
{
flag = 0;
p2 = p1;
p1 = p1->next;
if(p1->num == num)
{
flag = 1;
break;
}
}
if(flag == 1)
{
p1 = p2;
return p1;
}
else
{
printf("没有此人\n");
return NULL;
}
}
stuPtr delete(stuPtr head, int num) {
stuPtr p1,p2;
int flag;
p1 = search(head,num);
p2 = p1->next;
p1->next = p2->next;
free(p2);
stuwrite(head);
p1 = sturead();
return p1;
}
void print(stuPtr head)
{
stuPtr p;
int i;
printf("学号\t姓名\t成绩\n");
p = head->next;
while(p != NULL)
{
if(p->num >0 && p->grade >0)
{
printf("%d\t%s\t%.1f\n",p->num,p->name,p->grade);
}
p = p->next;
}
}
void print1(stuPtr p)
{
printf("学号\t姓名\t成绩\n");
while(p != NULL)
{
if(p->num >0 && p->grade >0)
{
printf("%d\t%s\t%.1f\n",p->num,p->name,p->grade);
}
p = p->next;
}
}
int main()
{
int choose,num;
stuPtr head,p;
head = (stuPtr)malloc(sizeof(stuNode));
p = (stuPtr)malloc(sizeof(stuNode));
while(1)
{
printf("1\t创建链表\n2\t添加节点\n3\t删除节点\n4\t查找学生\n5\t查看所有学生信息\n0\t退出\n");
scanf("%d",&choose);
switch(choose)
{
case 1:
creat();
break;
case 2:
head = sturead();
insert(head);
break;
case 3:
head = sturead();
printf("删除学生的学号：");
scanf("%d",&num);
delete(head,num);
break;
case 4:
head = sturead();
printf("学生学号：");
scanf("%d",&num);
p = search(head,num);
p = p->next;
print1(p);
break;
case 5:
head = sturead();
print(head);
case 0:
break;
default:
break;
}
}
return 0;
}