我创建了一个程序，该程序从用户那里获取帐户信息，并将其存储到文件 accounts.dat 中。由于该程序现在是正确的，因此看起来一切正常，直到我关闭它并重新打开以进行测试为止，它不会读取我已经输入的任何信息。情况6是应该从 accounts.dat 中读取的地方。每次使用 accounts.dat 时，似乎确实充满了信息。
/* HEADER FILES */
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
/* STRUCT TO HOLD ACCOUNT INFO */
struct bank
{
char first[25];
char middle[25];
char last[25];
long int aNumber;
float aBalance;
};
/* MAIN START*/
int main()
{
int choice; /* SWITCH-STATEMENT CASE */
int i; /* FOR-LOOP COUNTER */
int count; /* KEEPS TRACK OF TOTAL # OF ACCOUNTS */
long int aNumber; /* TEMPORARILY HOLDS ACCOUNT # FOR SEARCH IN FILE */
float amount; /* TEMPORARILY HOLDS A DOLLAR AMOUNT FOR VARIOUS REASONS */
FILE *fp; /* SPECIFIC FILE DECLARATION FOR OUR BANK */
struct bank account[50]; /* ARRAY DECLARATION FOR STRUCT */
/* DO/WHILE START */
do
{
/* OPTION MENU */
printf("\n\nWelcome to yor bank access.\n"
"Please follow the prompts below.\n\n"
"\t0. Exit\n"
"\t1. Deposit\n"
"\t2. Withdrawal\n"
"\t3. Add account\n"
"\t4. Remove Account\n"
"\t5. Balance Inquiry\n"
"\t6. View Account\n"
"\nEnter your choice: ");
scanf("%d",&choice);
printf("\n");
/* SWITCH START */
switch(choice)
{
/* CASE 0: EXIT PROGRAM */
case 0:
exit(1);
break;
/* CASE 1: DEPOSIT */
case 1:
fopen("accounts.dat", "r+");
fseek(fp,0,SEEK_SET);
printf("please enter account number: ");
scanf("%ld",&aNumber);
printf("Amount to be deposited: $");
scanf("%f", &amount);
for(i=0; i<count; i++)
{
if(account[i].aNumber == aNumber)
{
account[i].aBalance = account[i].aBalance + amount;
fseek(fp,i * sizeof(struct bank),SEEK_SET);
fwrite(account+i,sizeof(struct bank),1, fp);
break;
}
}
if(i==count)
printf("Account number does not exits\n");
break;
/* CASE:2 WITHDRAWAL */
case 2:
fopen("accounts.dat", "r+");
fseek(fp,0,SEEK_SET);
printf("Please enter account number: ");
scanf("%ld",&aNumber);
printf("Enter the amount to be withdrawn: $");
scanf("%f",&amount);
for(i=0; i<count; i++)
{
if(account[i].aNumber==aNumber)
{
if(account[i].aBalance<amount)
{
printf("Insufficient balance\n");
break;
}
account[i].aBalance=account[i].aBalance-amount;
fseek(fp,i*sizeof(struct bank),SEEK_SET);
fwrite(account+i,sizeof(struct bank),1, fp);
break;
}
}
if(i==count)
printf("Account number does not exits\n");
break;
/* CASE 3: ADD ACCOUNT */
case 3:
fp = fopen("accounts.dat","a+");
printf("Enter a 6-digit account number: ");
scanf("%ld",&aNumber);
for(i=0; i<count; i++)
{
if(account[i].aNumber==aNumber)
{
printf("Account already exist\n");
break;
}
}
if(i==count)
{
account[i].aNumber=aNumber;
printf("Enter the First Name: ");
scanf("%s",account[i].first);
printf("Enter the Middle Initial: ");
scanf("%s",account[i].middle);
printf("Enter the Last Name: ");
scanf("%s",account[i].last);
printf("Enter the Amount: $");
scanf("%f",&account[i].aBalance);
fseek(fp,0,SEEK_END);
fwrite(account+i,sizeof(struct bank),1, fp);
count++;
}
break;
/* CASE 4: DELETE ACCOUNT */
case 4:
fopen("accounts.dat", "a+");
fseek(fp,0,SEEK_SET);
printf("Please enter account number: ");
scanf("%ld",&aNumber);
for(i=0; i<count; i++)
{
if(account[i].aNumber==aNumber)
break;
}
if(i==count)
printf("Account number does not exits\n");
else
{
while(i<count)
{
strcpy(account[i].first,account[i+1].first);
strcpy(account[i].middle,account[i+1].middle);
strcpy(account[i].last,account[i+1].last);
account[i].aNumber=account[i+1].aNumber;
account[i].aBalance=account[i+1].aBalance;
}
count--;
fp=fopen("accounts.dat", "wb");
for(i=0; i<count; i++)
fwrite(account+i,sizeof(struct bank),1, fp);
fclose(fp);
/* REOPEN FILE */
fopen("accounts.dat", "r+");
}
break;
/* CASE 5: BALANCE INQUIRY*/
case 5:
fopen("accounts.dat", "r");
printf("Please enter account number: ");
scanf("%ld",&aNumber);
for(i=0; i<count; i++)
{
if(account[i].aNumber==aNumber)
{
printf("First Name: %s\n",account[i].first);
printf("Middle Initial: %s\n",account[i].middle);
printf("Last Name: %s\n",account[i].last);
printf("Account Number: %ld\n",account[i].aNumber);
printf("Balance Amount: $%.2f\n",account[i].aBalance);
break;
}
}
if(i==count)
printf("Account number does not exits\n");
break;
/* CASE 6: VIEW ACCOUNTS*/
case 6:
fopen("accounts.dat", "r");
for(i=0; i<count; i++)
{
fread(&account[i], sizeof(account), 1, fp);
printf("Entry %1d\n", i+1);
printf("First Name: %s\n",account[i].first);
printf("Middle Initial: %s\n",account[i].middle);
printf("Last Name: %s\n",account[i].last);
printf("Account Number: %ld\n",account[i].aNumber);
printf("Account Balance: $%.2f\n",account[i].aBalance);
}
} /* END SWITCH-STATEMENT */
} /* END 'DO' */
while(choice!=0);
return 0;
}
答案 0 :(得分：0)
在案例6中启动程序时， Debug.Log(offsets[0].ToString("F2")); // round off to 2 decimal places
未初始化，从而导致count循环的意外行为。
答案 1 :(得分：-1)
正如已经指出的那样，计数尚未初始化，但是当您退出程序并稍后重新启动时，计数通常从零开始。虽然不能保证此值，但如果为零，则会发现循环会提前终止。
因此，在重新启动时，您需要做的是读回dat文件中的记录数并将其初始化计数为该数，然后一切都应从那里开始。您可能需要创建一个“读取现有文件”或类似选项的新选项来进行扫描。