这是我的代码中的代码当我在file_pointer中添加一些记录时，我没有看到列表结果似乎fwrite不能很好地工作或者如果我的代码中出现错误，那么就会出现错误我把添加记录然后我试图列出它不会显示任何记录或我认为列表不能很好地工作
#include<stdio.h>
#include<string.h>
#include<conio.h>
#include<ctype.h>
#include<windows.h>
struct {
char studno[10];
char name[80];
char section[20];
int age;
}student[20];
FILE *file_pointer;
int t;
void add();
void list();
void gotoxy(int x, int y)
{
COORD coord;
coord.X = x;
coord.Y = y;
SetConsoleCursorPosition(GetStdHandle(STD_OUTPUT_HANDLE), coord);
}
int main()
{
int choice;
for(;;)
{
gotoxy(35,5);
printf("[1]Add Student Record\n");
gotoxy(28,10);
printf("[2]List Student Record\n");
gotoxy(28,12);
printf("[3]Exit\n\n");
gotoxy(35,15);
printf("Choice: ");
scanf("%d",&choice);
if(choice==1){
add();
system("cls");
}
else if(choice==2){
list();
system("cls");
}
else if(choice==3){
exit(0);
}
}
}
void add()
{
char ans;
int i;
for(i=0;i<20;i++){
system("cls");
gotoxy(31,2);
printf("ADD STUDENT RECORDS\n\n");
gotoxy(31,5);
printf("\t\t\t\tRecord Number: %d\n\n",i+1);
gotoxy(3,7);
printf("Student Number: ");
scanf("%s",&student[i].studno);
gotoxy(3,9);
printf("Name: ");
scanf("%s",&student[i].name);
gotoxy(3,11);
printf("Section: ");
scanf("%s",&student[i].section);
gotoxy(3,13);
printf("Age: ");
scanf("%d",&student[i].age);
t++;
if((file_pointer=fopen("student.dat","w"))!=NULL)
{
fwrite(student[i+1].studno,sizeof(student[i+1].studno),i,file_pointer);
gotoxy(31,18);
printf("\nAdd another? [Y/N]: ");
scanf("%s",&ans);
if(toupper(ans)=='N')
{
fclose(file_pointer);
i=20;
break;
system("cls");
}
}
else
{
printf("Error writing student.dat\n");
fclose(file_pointer);
gotoxy(31,18);
printf("\nAdd another? [Y/N]: ");
scanf("%s",&ans);
if(toupper(ans)=='N')
{
i=20;
break;
system("cls");
}
}
}
}
void list()
{
system("cls");
int i,x=0,y=8;
gotoxy(31,2);
printf("LIST STUDENT RECORD\n\n");
gotoxy(3,5);
printf("Record No.");
gotoxy(3,6);
printf("-------------");
gotoxy(19,5);
printf("Student No.");
gotoxy(19,6);
printf("-------------");
gotoxy(35,5);
printf("Name");
gotoxy(35,6);
printf("-------------");
gotoxy(59,5);
printf("Section");
gotoxy(59,6);
printf("-------------");
gotoxy(73,5);
printf("Age");
gotoxy(73,6);
printf("-------------");
for(i = 0;i<t;)
{
if((file_pointer=fopen("student.dat","r"))!=NULL)
{
fread(student[i+1].studno,sizeof(student[i+1].studno),i,file_pointer);
}
else
{
printf("Error writing student.dat\n");
fclose(file_pointer);
gotoxy(x+3,y);
printf(" -%d-",i+1);
gotoxy(x+23,y);
printf("%s",student[i].studno);
gotoxy(x+35,y);
printf("%s",student[i].name);
gotoxy(x+59,y);
printf("%s",student[i].section);
gotoxy(x+73,y);
printf("%d",student[i].age);
y++;
}
fclose(file_pointer);
i=t;
}
getch();
}
答案 0 :(得分：0)
在add()，
for(i=0;i<20;i++){
...
fwrite(student[i+1].studno,sizeof(student[i+1].studno),i,file_pointer);
...
}
对于i = 0，fwrite将0 * sizeof(student[i+1].studno)个字节的数组写入file_pointer指向的内存块，最后一次迭代i = 19写入19 * sizeof(student[i+1].studno)的数组字节不是你想要的。