我必须建立一个图书馆管理系统，只是为了练习而我（主要是）。每当我重新执行程序时，都会根据新的运行覆盖给予书籍ID，名称等的值。如何防止这种情况并将数据存储在最后一次运行中？
#include <stdio.h>
#include <stdlib.h>
typedef struct Book
{
char *bname[40];
int ssnid;
int location;
int issuedate;
int issuemonth;
int returndate;
int returnmonth;
}book;
typedef struct Student
{
char *sname[30];
int sid;
int count;
}student;
void addbook(book lbook[10],int num)
{
int i;
FILE *fptr;
printf("enter the book name \t");
fflush(stdin);
gets(lbook[num].bname);
lbook[num].location=0;
lbook[num].issuedate=0;
lbook[num].issuemonth=0;
lbook[num].returndate=0;
lbook[num].returnmonth=0;
label:
printf("\nenter the SSN ID :\t");
scanf("%d",&lbook[num].ssnid);
for(i=0;i<num;i++)
{
if(lbook[i].ssnid==lbook[num].ssnid)
{
printf("\nthis id has already been used\n");
goto label;
}
}
fptr=fopen("book.txt","a");
fprintf(fptr,"\nbook number %d \nbook name :\t",num+1);
fputs(lbook[num].bname,fptr);
fprintf(fptr,"\n book SSN ID %d",lbook[num].ssnid);
fclose(fptr);
}
void addstudent(student lstudent[10],int snum)
{
int i;
FILE *fptr;
printf("enter the student name \t");
fflush(stdin);
gets(lstudent[snum].sname);
lstudent[snum].count=0;
label2:
printf("\nenter the ID :\t");
scanf("%d",&lstudent[snum].sid);
for(i=0;i<snum;i++)
{
if(lstudent[i].sid==lstudent[snum].sid)
{
printf("\nthis id has already been used\n");
goto label2;
}
}
fptr=fopen("student.txt","a");
fprintf(fptr,"\nstudent number %d \nstudent name :\t",snum+1);
fputs(lstudent[snum].sname,fptr);
fprintf(fptr,"\n student ID %d",lstudent[snum].sid);
fclose(fptr);
}
/*void delbook(book lbook[10],int num,int bnum)
{
FILE *fptr;
int i,n;
for(n=num;n<bnum+1;n++)
{
strcpy(lbook[10].bname,lbook[n].bname);
lbook[10].ssnid=lbook[n].ssnid;
strcpy(lbook[n].bname,lbook[n+1].bname);
lbook[n].ssnid=lbook[n+1].ssnid;
strcpy(lbook[n+1].bname,lbook[10].bname);
lbook[n+1].ssnid=lbook[10].ssnid;
}
lbook[bnum].ssnid=0;
fptr=fopen("book.txt","w");
for(i=0;i<bnum;i++)
{fprintf(fptr,"\nbook number %d \nbook name :\t",i+1);
fputs(lbook[i].bname,fptr);
fprintf(fptr,"\n book SSN ID %d",lbook[i].ssnid);
}
fclose(fptr);
}*/
void issuebook(book lbook[10],student lstudent[10],int bnum,int snum)
{
int nb,i,ns,j;
int date,month;
FILE *cptr;
printf("\nenter book id to be issued\t");
scanf("%d",&nb);
for(i=0;i<bnum;i++)
{
if(lbook[i].ssnid==nb)
{
if(lbook[i].location==0)
{
printf("\nenter the student id: \t");
scanf("%d",&ns);
for(j=0;j<snum;j++)
{
if(lstudent[j].sid==ns)
{
if(lstudent[j].count==0||lstudent[j].count==1)
{
printf("\nenter date :\t");
scanf("%d",&lbook[i].issuedate);
printf("\nenter month :\t");
scanf("%d",&lbook[i].issuemonth);
lbook[i].location=lstudent[j].sid;
lstudent[j].count++;
cptr=fopen("log.txt","a");
fprintf(cptr,"\nbook id %d issued by student id %d date on
%d month %d",lbook[i].ssnid,lstudent[j].sid,lbook[i].issuedate,lbook[i].issuemonth);
fclose(cptr);
}
else{printf("\nlimit reached i.e. 2 books already issued\n");}
}
}
}
else{printf("book already issued\n");}
}
/* else
{
printf("\nbook not available\n");
}*/
}
}
void returnbook(book lbook[10],student lstudent[10],int bnum,int snum)
{
int nb,i,ns,j;
int date,month,dcount;
FILE *cptr;printf("\nenter book id to be returned\t");
scanf("%d",&nb);
for(i=0;i<bnum;i++)
{
if(lbook[i].ssnid==nb)
{
if(lbook[i].location!=0)
{
printf("\nenter the student id: \t");
scanf("%d",&ns);
for(j=0;j<snum;j++)
{
if(lstudent[j].sid==ns)
{
//if(lstudent[j].count==0||lstudent[j].count==1)
//{
printf("\nenter return date :\t");
scanf("%d",&lbook[i].returndate);
printf("\nenter return month :\t");
scanf("%d",&lbook[i].returnmonth);
printf("\nissue date \t%d",lbook[i].issuedate);
printf("\nissue month%d",lbook[i].issuemonth);
printf("\nenter days between issue and return\t");
scanf("%d",&dcount);
if(dcount>7)
{printf("fine :%d \t",(dcount-7)*20);}
lbook[i].location=0;
lstudent[j].count--;
cptr=fopen("log.txt","a");
fprintf(cptr,"\nbook id %d returned by student id %d on date %d month
%d",lbook[i].ssnid,lstudent[j].sid,lbook[i].returndate,lbook[i].returnmonth
);
if(dcount>7)
{fprintf(cptr,"\n fine payed of rs. %d ",(dcount-7)*20);}
fclose(cptr);
//}
//else{printf("\nlimit reached i.e. 2 books already issued\n");}
}
}
}
else{printf("book already in library\n");}
}
}
}
void displaybook()
{
FILE *fptr;
char ch;
fptr=fopen("book.txt","r");
ch=fgetc(fptr);
while(ch!=EOF)
{
putchar(ch);
ch=fgetc(fptr);
}
fclose(fptr);
}
void displaystudent()
{
FILE *fptr;
char ch;
fptr=fopen("student.txt","r");
ch=fgetc(fptr);
while(ch!=EOF)
{
putchar(ch);
ch=fgetc(fptr);
}
fclose(fptr);
}
int main()
{
book lbook[10];
student lstudent[10];
int bnum=0;
int snum=0;
char ch;
int i;
int delid;
int choice;
FILE *fptr;
fptr=fopen("book.txt","r");
for(i=0;i<10;i++)
{
fscanf(fptr,"%d",lbook[i].ssnid);
fscanf(fptr,"%d",lbook[i].issuedate);
fscanf(fptr,"%d",lbook[i].issuemonth);
fscanf(fptr,"%d",lbook[i].returndate);
fscanf(fptr,"%d",lbook[i].returnmonth);
fscanf(fptr,"%d",lbook[i].location);
fgets(lbook[i].bname,1,fptr);
}
fclose(fptr);
fptr=fopen("student.txt","r");
for(i=0;i<10;i++)
{
fscanf(fptr,"%d",lstudent[i].sid);
fscanf(fptr,"%d",lstudent[i].count);
fgets(lstudent[i].sname,1,fptr);
}
fclose(fptr);
printf("\t \t \tLIBRARY MANAGEMENT SYSTEM\n");
do{
printf("enter 1.for adding a book\tenter 2.for adding a student\n3.for
deleting a book\t4.for issuing a book\n5.for returning book\n");
printf("enter 6 display books\tenter 7 for display students\n");
scanf("%d",&choice);
switch(choice)
{
case 1:if(bnum<10)
{
addbook(lbook,bnum);
bnum++;
}
else{printf("\nbooks complete\n");}
break;
case 2:if(snum<10)
{
addstudent(lstudent,snum);
snum++;
}
else{printf("\nstudents complete\n");}
break;
/* case 3: printf("\nenter id to delete\t");
scanf("%d",&delid);
delbook(lbook,delid,bnum);
bnum--;
break;*/
case 4:issuebook(lbook,lstudent,bnum,snum);
break;
case 5:returnbook(lbook,lstudent,bnum,snum);
break;
case 6:displaybook();
break;
case 7:displaystudent();
break;
case 8:
break;
}
printf("enter y to continue\t");
scanf("%s",&ch);
}while(ch=='y');
}
答案 0 :(得分：0)
首先，我只是说你的答案需要Minimal, Complete, and Verifiable部分。
但接下来，我没有阅读你的所有代码，但这是我从你的问题中得到的：
我很确定你在存储记录方面遇到了麻烦。
一种选择是将其存储在像SQLite这样的数据库中（它作为文件存储在本地，因此不需要服务器）
答案 1 :(得分：0)
一个问题是用addbook（3个项目）写的文件与main（7个项目）中试图读取的文件不匹配。
通常不要混用scanf和fgets。使用fgets进行所有输入，并根据需要使用sscanf进行解析。不要使用gets。
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct Book
{
char bname[40];
int ssnid;
int location;
int issuedate;
int issuemonth;
int returndate;
int returnmonth;
}book;
typedef struct Student
{
char sname[30];
int sid;
int count;
}student;
void addbook(book lbook[10],int num)
{
char line[200] = "";
int i;
int result = 0;
FILE *fptr;
printf("enter the book name \t");
fflush(stdout);
fgets(lbook[num].bname, sizeof lbook[num].bname, stdin);
lbook[num].bname[strcspn ( lbook[num].bname, "\n")] = '\0';//remove newline
lbook[num].location=0;
lbook[num].issuedate=0;
lbook[num].issuemonth=0;
lbook[num].returndate=0;
lbook[num].returnmonth=0;
while ( 1) {
do {
printf("\nenter the SSN ID :\t");
fgets ( line, sizeof line, stdin);
result = sscanf(line, "%d",&lbook[num].ssnid);
} while ( result != 1);
for(i=0;i<num;i++)
{
if(lbook[i].ssnid==lbook[num].ssnid)
{
printf("\nthis id has already been used\n");
continue;
}
}
break;
}
fptr=fopen("book.txt","a");
fprintf(fptr,"%d ",lbook[i].ssnid);
fprintf(fptr,"%d ",lbook[i].issuedate);
fprintf(fptr,"%d ",lbook[i].issuemonth);
fprintf(fptr,"%d ",lbook[i].returndate);
fprintf(fptr,"%d ",lbook[i].returnmonth);
fprintf(fptr,"%d ",lbook[i].location);
fprintf(fptr,"%s\n",lbook[num].bname);
fclose(fptr);
}
void addstudent(student lstudent[10],int snum)
{
char line[200] = "";
int i;
int result = 0;
FILE *fptr;
printf("enter the student name \t");
fflush(stdout);
fgets(lstudent[snum].sname, sizeof lstudent[snum].sname, stdin);
lstudent[snum].sname[strcspn ( lstudent[snum].sname, "\n")] = '\0';//remove newline
lstudent[snum].count=0;
while ( 1) {
do {
printf("\nenter the ID :\t");
fgets ( line, sizeof line, stdin);
result = sscanf(line, "%d",&lstudent[snum].sid);
} while ( result != 1);
for(i=0;i<snum;i++)
{
if(lstudent[i].sid==lstudent[snum].sid)
{
printf("\nthis id has already been used\n");
continue;
}
}
break;
}
fptr=fopen("student.txt","a");
fprintf(fptr,"%d %d %s\n",lstudent[snum].sid, lstudent[snum].count, lstudent[snum].sname);
fclose(fptr);
}
void issuebook(book lbook[10],student lstudent[10],int bnum,int snum)
{
char line[200] = "";
int nb,i,ns,j;
int result = 0;
FILE *cptr;
do {
printf("\nenter book id to be issued\t");
fgets ( line, sizeof line, stdin);
result = sscanf( line, "%d",&nb);
} while ( result != 1);
for(i=0;i<bnum;i++)
{
if(lbook[i].ssnid==nb)
{
if(lbook[i].location==0)
{
do {
printf("\nenter the student id: \t");
fgets ( line, sizeof line, stdin);
result = sscanf(line, "%d",&ns);
} while ( result != 1);
for(j=0;j<snum;j++)
{
if(lstudent[j].sid==ns)
{
if(lstudent[j].count==0||lstudent[j].count==1)
{
do {
printf("\nenter date :\t");
fgets ( line, sizeof line, stdin);
result = sscanf(line, "%d",&lbook[i].issuedate);
} while ( result != 1);
do {
printf("\nenter month :\t");
fgets ( line, sizeof line, stdin);
result = sscanf(line, "%d",&lbook[i].issuemonth);
} while ( result != 1);
lbook[i].location=lstudent[j].sid;
lstudent[j].count++;
cptr=fopen("log.txt","a");
fprintf(cptr,"\nbook id %d issued by student id %d date on %d month %d"
,lbook[i].ssnid,lstudent[j].sid,lbook[i].issuedate,lbook[i].issuemonth);
fclose(cptr);
}
else{
printf("\nlimit reached i.e. 2 books already issued\n");
}
}
}
}
else{printf("book already issued\n");}
}
}
}
void returnbook(book lbook[10],student lstudent[10],int bnum,int snum)
{
int nb,i,ns,j;
int dcount;
int result = 0;
char line[200] = "";
FILE *cptr;
do {
printf("\nenter book id to be returned\t");
fgets ( line, sizeof line, stdin);
result = sscanf(line, "%d",&nb);
} while ( result != 1);
for(i=0;i<bnum;i++)
{
if(lbook[i].ssnid==nb)
{
if(lbook[i].location!=0)
{
do {
printf("\nenter the student id: \t");
fgets ( line, sizeof line, stdin);
result = sscanf(line, "%d",&ns);
} while ( result != 1);
for(j=0;j<snum;j++)
{
if(lstudent[j].sid==ns)
{
do {
printf("\nenter return date :\t");
fgets ( line, sizeof line, stdin);
result = sscanf(line, "%d",&lbook[i].returndate);
} while ( result != 1);
do {
printf("\nenter return month :\t");
fgets ( line, sizeof line, stdin);
result = sscanf(line, "%d",&lbook[i].returnmonth);
} while ( result != 1);
printf("\nissue date \t%d",lbook[i].issuedate);
printf("\nissue month%d",lbook[i].issuemonth);
do {
printf("\nenter days between issue and return\t");
fgets ( line, sizeof line, stdin);
result = sscanf(line, "%d",&dcount);
} while ( result != 1);
if(dcount>7)
{
printf("fine :%d \t",(dcount-7)*20);
}
lbook[i].location=0;
lstudent[j].count--;
cptr=fopen("log.txt","a");
fprintf(cptr,"\nbook id %d returned by student id %d on date %d month %d"
,lbook[i].ssnid,lstudent[j].sid,lbook[i].returndate,lbook[i].returnmonth
);
if(dcount>7)
{
fprintf(cptr,"\n fine payed of rs. %d ",(dcount-7)*20);
}
fclose(cptr);
}
}
}
else{printf("book already in library\n");}
}
}
}
void displaybook()
{
FILE *fptr;
char line[200] = "";
if ( NULL != ( fptr=fopen("book.txt","r"))) {
while(fgets ( line, sizeof line, fptr))
{
printf ( "%s",line);
}
fclose(fptr);
}
else {
printf ( "no books to show\n");
}
}
void displaystudent()
{
FILE *fptr;
char line[200] = "";
if ( NULL != ( fptr=fopen("student.txt","r"))) {
while(fgets ( line, sizeof line, fptr))
{
printf ( "%s",line);
}
fclose(fptr);
}
else {
printf ( "no students to show\n");
}
}
int main()
{
book lbook[10];
student lstudent[10];
int bnum=0;
int snum=0;
char line[200] = "";
int i;
FILE *fptr;
if ( NULL != ( fptr=fopen("book.txt","r"))) {
i = 0;
while ( i < 10 && fgets ( line, sizeof line, fptr)) {
if ( 7 == sscanf(line,"%d %d %d %d %d %d %39[^\n]"
, &lbook[i].ssnid
, &lbook[i].issuedate
, &lbook[i].issuemonth
, &lbook[i].returndate
, &lbook[i].returnmonth
, &lbook[i].location
, lbook[i].bname)) {
i++;
}
}
fclose(fptr);
}
if ( NULL != ( fptr=fopen("student.txt","r"))) {
i = 0;
while ( i < 10 && fgets ( line, sizeof line, fptr)) {
if ( 3 == sscanf(line,"%d %d %29[^\n]"
, &lstudent[i].sid
, &lstudent[i].count
, lstudent[i].sname)) {
i++;
}
}
fclose(fptr);
}
do{
printf("\n\n\t\t\tLIBRARY MANAGEMENT SYSTEM\n");
printf ( "\t\t1 (for adding a book)\n\t\t2 (for adding a student)\n");
printf ( "\t\t3 (for deleting a book)\n\t\t4 (for issuing a book)\n\t\t5 (for returning book)\n");
printf ( "\t\t6 (display books)\n\t\t7 (for display students)\n\t\t8 ( quit)\n");
printf("\tchoice: ");
fflush ( stdout);
fgets ( line, sizeof line, stdin);
switch( line[0])
{
case '1':
if(bnum<10)
{
addbook(lbook,bnum);
bnum++;
}
else{printf("\nbooks complete\n");}
break;
case '2':
if(snum<10)
{
addstudent(lstudent,snum);
snum++;
}
else{printf("\nstudents complete\n");}
break;
case '4':
issuebook(lbook,lstudent,bnum,snum);
break;
case '5':
returnbook(lbook,lstudent,bnum,snum);
break;
case '6':
displaybook();
break;
case '7':
displaystudent();
break;
case '8':
return 0;
default:
printf ( "\n\tnot a valid choice\n\n");
break;
}
printf("enter y to continue\t");
fgets ( line, sizeof line, stdin);
}while(line[0]=='y');
}