不用链表，单是结构体写入文件后，是否可以进行修改删除

#include

#include

#include

typedef struct Node

{

char  num[20];

char name[20];

}STU;

void add();

void read(char *);

void delete();

void visit();

int main()

{

while(1)

{

printf("1  add\n");

printf("2  delete\n");

int i;

scanf("%d",&i);

switch(i)

{

case 1:

add();

break;

case 2:

{

visit();

delete();

printf("===========================\n");

visit();

break;

}

default:

break;

}

}

return 0;

}

void delete()

{

char p[128];

char num[128];

int i=0;

FILE *fp=fopen("stu.txt","r+");

if(fp == NULL)

{

printf("文件不存在！\n");

exit(1);

}

STU *stu2=(STU *)malloc(sizeof(STU));

printf("输入需要删除的num!\n");

scanf("%s",num);

rewind(fp);

while(1)

{

fseek(fp,i*sizeof(STU),SEEK_SET);

fread(stu2,sizeof(STU),1,fp);

if(strcmp(p,stu2->num)==0)

{

break;

}

if(strcmp(num,stu2->num)==0)

{

free(stu2);

strcpy(stu2->num,"");

strcpy(stu2->name,"");

break;

}

strcpy(p,stu2->num);

i++;

}

fclose(fp);

}

void add()

{

FILE *fp=fopen("stu.txt","a+");

STU *stul=(STU *)malloc(sizeof(STU));

printf("请输入编号：\n");

scanf("%s",stul->num);

printf("请输入姓名：\n");

scanf("%s",stul->name);

if(fgetc(fp) != EOF)

{

read(stul->num);

}

fwrite(stul,sizeof(STU),1,fp);

fclose(fp);

}

void read(char *num)

{

char p[128]="abcd";

int i=0;

FILE *fp = fopen("stu.txt","r");

STU *stu2=(STU *)malloc(sizeof(STU));

rewind(fp);

while(1)

{

fseek(fp,i*sizeof(STU),SEEK_SET);

fread(stu2,sizeof(STU),1,fp);

if(strcmp(p,stu2->num)==0)

{

break;

}

if(strcmp(num,stu2->num)==0)

{

printf("用户名已经存在！\n");

break;

}

strcpy(p,stu2->num);

i++;

}

fclose(fp);

}

void visit()

{

char p[128]="abcd";

int i=0;

FILE *fp=fopen("stu.txt","r");

STU *stu2=(STU *)malloc(sizeof(STU));

rewind(fp);

while(1)

{

fseek(fp,i*sizeof(STU),SEEK_SET);

fread(stu2,sizeof(STU),1,fp);

if(strcmp(p,stu2->num)==0)

{

break;

}

printf("第%d次：%s  %s\n",i,stu2->num, stu2->name);

strcpy(p,stu2->num);

i++;

}

fclose(fp);

}

不用链表，单是结构体好像不能进行修改删除动作，上述代码只是实现了读和写，删除没有实现，各位大大可否帮忙，谢谢了！