（笔记！）
#include#include#includestruct STU
{char name[20];
int num;
int age;
char addr[20];
};
struct Jd
{struct STU student;
struct Jd *next;
};
void createFile(char *FName); //创建文件，存放结构体数据
void readFile(char *FName); //从文件读出数据到结构体
struct Jd *createchain(char *FName); //利用文件创建链表
void printchain(struct Jd *head); //输出链表所有结点数据
void sortchain(struct Jd *head); //根据地址对链表进行排序
void writeToFile(struct Jd *head, char *FName); //把链表结点数据写往文件
int main(void)
{struct Jd *head = NULL;
char FileName[128] = {'\0'};
strcpy(FileName,"stu.dat");
createFile(FileName);
readFile(FileName);
head = createchain(FileName);
printf("* * * * * 未排序的链表数据 * * * * * \n");
printchain(head);
sortchain(head);
printf("* * * * * 根据地址排序后的链表数据 * * * * * \n");
printchain(head);
strcpy(FileName, "paixu.dat");
writeToFile(head,FileName);
readFile(FileName);
return 0;
}
void createFile(char *FName)
{int i = 1;
struct STU stud;
FILE *fp;
if ( (fp = fopen(FName, "wb")) == NULL ) //利用FName的字符串作文件名
{printf("cannot open file\n");
exit(0);
}
while ( i!=0 )
{printf("enter data of student:\n");
printf("姓名：");
scanf("%s", stud.name);
printf("学号：");
scanf("%d", &stud.num);
printf("年龄：");
scanf("%d", &stud.age);
printf("地址：");
scanf("%s", stud.addr);
if ( fwrite(&stud,sizeof(struct STU),1,fp) != 1 ) //把一个结构体数据写到文件中，并判断是否真实写入
{ printf("file write error\n");
}
printf("还需要输入新的学生数据(1=继续，0=退出)");
scanf("%d", &i);
}
fclose(fp);
}
void readFile(char *FName)
{struct STU stud;
FILE *fp;
if ( (fp = fopen(FName, "rb")) == NULL )
exit(0);
printf("* * * * * %s 文件中的记录数据 * * * * * \n", FName);
//从文件里读出一个结构体数据，知道读不出一个完整的结构体数据
while ( fread(&stud,sizeof(struct STU),1,fp) == 1 )
{printf("%-20s %4d %4d %-20s\n", stud.name, stud.num, stud.age, stud.addr);
}
fclose(fp);
}
struct Jd *createchain(char *FName)
{FILE *fp;
struct Jd *pt, *pEnd, *head = NULL;
struct STU stud;
if ( (fp=fopen(FName,"rb")) == NULL )
{exit(0);
}
while ( fread(&stud, sizeof(struct STU), 1, fp) == 1 ) //从文件里读出一个结构体数据
{pt = (struct Jd *)malloc(sizeof(struct Jd)); //创建链表结点空间
pt->student = stud; //把前面读出的结构体数据赋值给结点的student成员
if ( head == NULL )
{ head = pEnd = pt;
pt->next = NULL;
}
else //在尾部插入结点
{ pEnd->next = pt; //将新结点链入链表
pt->next = NULL; //将新结点的next指针置空，标识成尾结点
pEnd = pt; //让pEnd指向尾结点，为下一次插入做准备
}
}
fclose(fp);
return head;
}
void printchain(struct Jd *head)
{struct STU stud;
while ( head != NULL ) //从头结点开始输出，直到链表最后的尾结点
{stud = head->student;
printf("%-20s %4d %4d %-20s\n", stud.name, stud.num, stud.age, stud.addr);
head = head->next;
}
}
void sortchain(struct Jd *head) //根据addr的值从小到大的排序
{struct Jd *pt1, *pt2, *pt;
struct STU temp;
for ( pt1 = head; pt1->next != NULL; pt1 = pt1->next )
{pt = pt1;
for ( pt2 = pt1->next; pt2 != NULL; pt2 = pt2->next )
{ if ( strcmp(pt->student.addr,pt2->student.addr) >0 )
pt = pt2;
}
if ( pt != pt1 )
{ temp = pt1->student;
pt1->student = pt->student;
pt->student = temp;
}
}
}
void writeToFile(struct Jd *head, char *FName)
{FILE *fp;
struct Jd *pt;
if ( (fp = fopen(FName,"wb")) == NULL)
{exit(0);
}
pt = head;
//依次把链表结点的学生信息写往文件中，直到输出链表最后一个结点
while ( pt != NULL )
{fwrite(&(pt->student), sizeof(struct STU), 1, fp); //只将链表中学生信息写入
pt = pt->next;
}
fclose(fp);
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