在试用您的程序时，我也无法列出任何帐户信息，因为帐户名实际上是由带有嵌入空格的字符串组成的。在前面的代码中使用过“scanf”函数和带有嵌入空格的字符串之后，我确实尝试了一些使用格式化文字“%[^\n]”的重构代码，正如上面的好评所指出的。然而，为了使格式化文字工作也需要对帐户信息文件进行调整。
首先，下面是对“fscanf”函数进行了改进的程序重构版本。

#include <stdio.h>
#include <time.h>
#include <string.h>
#include <stdlib.h>

#define USER_PASS "./username.txt"
#define ACCOUNT_DATA "./AccountInfo.txt"

typedef struct
{
    char Name[30];
    char AccountType[20];
    long long AccountNo;
    long long Balance;
    long long Phone;
    long long NID;
    char Username[30];
} AccountInfo;

int loginverify(char *userid, char *pass);
void createaccount();
void mainmenu(char *usernm);
int ReadAccountInfo();
void ViewAccounts(char *usrnm, int sumaccounts);
void SearchAndPrint(char *username);

int main()
{
    int flag, signinoption;
    char user_name[20], password[30];
    printf("Welcome to My Bank\n");
    while (1)
    {
        printf("1. Login\n");
        printf("2. Create a new account\n");
        printf("3. Exit\n");
        printf("Choose your option: ");
        scanf("%d", &signinoption);
        printf("\n");
        switch (signinoption)
        {
        case 1:
            while (1)
            {
                printf("Enter Username: ");
                scanf("%19s", user_name);
                printf("Enter Password: ");
                scanf("%29s", password);
                flag = loginverify(user_name, password);

                if (flag == 1)
                {
                    printf("\nLogin successful. \n");
                    printf("\n");
                    mainmenu(user_name);
                    break;
                }
                else
                {
                    printf("Login Failed. Try again. \n");
                    printf("\n");
                }
            }
            break;
        case 2:
            createaccount();
            break;
        case 3:
            return 0;
            break;
        }
        if (signinoption == 1)
            break;
    }
    return 0;
}

void mainmenu(char *usernm)
{
    int menuchoice = 100;
    char usrnm[30];
    strcpy(usrnm, usernm);
    while (menuchoice != 12)
    {

        printf("1. View All Accounts\n");
        printf("2. Check Balance\n");
        printf("3. Cash Deposit\n");
        printf("4. Cash Withdraw\n");
        printf("5. Fund Transfer\n");
        printf("6. Benificiary Management\n");
        printf("7. Mini Statement\n");
        printf("8. Account Settings\n");
        printf("9. Close Account\n");
        printf("10. ATM/Branch Locations\n");
        printf("11. Customer Support\n");
        printf("12. Exit\n");

        printf("\n");
        printf("Choose your option: ");
        scanf("%d", &menuchoice);
        printf("\n");

        if (menuchoice == 1)
            SearchAndPrint(usrnm);
    }
}

int loginverify(char *userid, char *pass)
{
    FILE *fp;
    char user[20], password[30];
    int found = 0;

    fp = fopen(USER_PASS, "r");
    if (fp == NULL)
    {
        printf("Error: Could not open file\n");
        return 0;
    }

    while (fscanf(fp, "Username: %s\nPassword: %s\n", user, password) == 2)
    {
        if (strcmp(userid, user) == 0 && strcmp(pass, password) == 0)
        {
            found = 1;
            break;
        }
    }

    fclose(fp);
    return found;
}

void createaccount()
{
    char username[20], password[20];
    printf("Enter your login credentials: \n");
    // a function can be added to check uniquenness
    printf("Enter Username: ");
    scanf("%s", username);
    printf("Enter Password: ");
    scanf("%s", password);
    printf("\n");
    printf("Enter your Account details: \n");
    printf("Enter your Name: ");
    printf("Enter your Account Type (Savings/Current/Fixed Deposit): ");
    // here unique account number is requires. or it can be generated automatically
    printf("Enter your Account No: ");
    printf("Enter your Balance: ");
    printf("Enter your Phone No: ");
    printf("Enter your NID No: ");
    printf("\n");
    printf("Account Created Successfully\n");
    printf("\n");
}

void SearchAndPrint(char *username)
{
    printf("User Name: %s\n", username);
    FILE *fp;
    AccountInfo acc;
    int found = 0;

    fp = fopen(ACCOUNT_DATA, "r");
    if (fp == NULL)
    {
        printf("Error: Could not open file\n");
        return;
    }

    while (fscanf(fp, "Name: %[^\n] \nAccount Type: %s\nAccount No: %lld\nBalance: %lld\nPhone: %lld\nNID No: %lld\nUsername: %s\n", acc.Name, acc.AccountType, &acc.AccountNo, &acc.Balance, &acc.Phone, &acc.NID, acc.Username) == 7)
    {
        if (strcmp(username, acc.Username) == 0)
        {
            printf("Name: %s\nAccount Type: %s\nAccount No: %lld\nBalance: %lld\nPhone: %lld\nNID No: %lld\n\n", acc.Name, acc.AccountType, acc.AccountNo, acc.Balance, acc.Phone, acc.NID);
            found = 1;
        }
    }

    fclose(fp);

    if (!found)
    {
        printf("No matching accounts found\n");
    }
}

需要注意的一些关键点。

• 输入文字已更改为“%[^\n]”，并在该文字和换行符名称后添加了一个尾随空格，同时在帐户信息文件中的用户名后添加了一个空格。
• 为了美观起见，在“SearchAndPrint”函数中打印用户名值时做了一些小的调整。

经过这些调整后，下面是针对一个帐户测试程序的终端输出。

@Vera:~/C_Programs/Console/Banking/bin/Release$ ./Banking 
Welcome to My Bank
1. Login
2. Create a new account
3. Exit
Choose your option: 1

Enter Username: ElizabethSmith
Enter Password: G7FkPvHd3m

Login successful. 

1. View All Accounts
2. Check Balance
3. Cash Deposit
4. Cash Withdraw
5. Fund Transfer
6. Benificiary Management
7. Mini Statement
8. Account Settings
9. Close Account
10. ATM/Branch Locations
11. Customer Support
12. Exit

Choose your option: 1

User Name: ElizabethSmith
Name: Elizabeth Smith
Account Type: Savings
Account No: 6549873214
Balance: 93750
Phone: 8801912345678
NID No: 124356789

1. View All Accounts
2. Check Balance
3. Cash Deposit
4. Cash Withdraw
5. Fund Transfer
6. Benificiary Management
7. Mini Statement
8. Account Settings
9. Close Account
10. ATM/Branch Locations
11. Customer Support
12. Exit

Choose your option: 12

给予这些调整，看看它是否符合您项目的精神。