在这个收入管理中我的删除记录功能不起作用

问题描述 投票：0回答：1

在此代码中，我想从文件中删除用户的特定记录，但我无法这样做。 我使用这种方法来覆盖文件。首先，我制作了一个临时文件，在其中写入了所有其他记录，但我必须删除的记录除外。现在我删除了原始文件并将临时文件重命名为原始文件。

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

struct taxpayer
{
    char name[50];
    int Pancard_Number;
    int Mobileno;
    float income;
    float tax;
};

void add_record(FILE *file)
{
    struct taxpayer record;
    printf("Enter name: ");
    scanf("%s", record.name);
    printf("Enter 5-digit Pancard_number: ");
    scanf("%d", &record.Pancard_Number);
    printf("Enter Mobileno: ");
    scanf("%d", &record.Mobileno);
    printf("Enter income: ");
    scanf("%f", &record.income);

    if (record.income <= 25000)
    {
        record.tax = 0;
    }
    else if (record.income > 25000 && record.income <= 50000)
    {
        record.tax = (record.income - 25000) * 0.05;
    }
    else if (record.income > 50000 && record.income <= 75000)
    {
        record.tax = 1250 + ((record.income - 50000) * 0.2);
    }
    else if (record.income > 75000 && record.income <= 100000)
    {
        record.tax = 5520 + ((record.income - 75000) * 0.3);
    }
    else
    {
        record.tax = 11250 + ((record.income - 100000) * 0.4);
    }

    // record.tax = record.income * 0.1; // 10% tax rate
    fwrite(&record, sizeof(struct taxpayer), 1, file);
    printf("Record added successfully.\n");
}

void show_allrecord(FILE *file)
{
    // rewind(file);
    struct taxpayer record;
    fseek(file, 0, SEEK_SET);
    printf("%-20s %-20s %-20s %-20s  \n", "Name", "PancardNo.", "Income", "TaxPaid");
    while (fread(&record, sizeof(struct taxpayer), 1, file))
    {
        printf("%-20s %-19d Rs.%-19.2f Rs.%-17.2f  \n", record.name, record.Pancard_Number, record.income, record.tax);
    }
}

void search_record(FILE *file)
{
    // char name[50];
    int search;
    struct taxpayer record;
    printf("Enter pancard number to search: ");
    scanf("%d", &search);
    fseek(file, 0, SEEK_SET);
    while (fread(&record, sizeof(struct taxpayer), 1, file))
    {
        if (record.Pancard_Number == search)
        {
            printf("%-20s %-20s %-20s %-20s  \n", "Name", "PancardNo.", "Income", "TaxPaid");

            printf("%-20s %-19d Rs.%-19.2f Rs.%-17.2f  \n", record.name, record.Pancard_Number, record.income, record.tax);

            return;
        }
    }
    printf("Record not found.\n");
}

void edit_record(FILE *file)
{
    char name[50];
    struct taxpayer record;
    printf("Enter name to edit: ");
    scanf("%s", name);
    fseek(file, 0, SEEK_SET);
    while (fread(&record, sizeof(struct taxpayer), 1, file))
    {
        if (strcmp(record.name, name) == 0)
        {
            printf("Enter new income: ");
            scanf("%f", &record.income);

            if (record.income <= 25000)
            {
                record.tax = 0;
            }
            else if (record.income > 25000 && record.income <= 50000)
            {
                record.tax = (record.income - 25000) * 0.05;
            }
            else if (record.income > 50000 && record.income <= 75000)
            {
                record.tax = 1250 + ((record.income - 50000) * 0.2);
            }
            else if (record.income > 75000 && record.income <= 100000)
            {
                record.tax = 5520 + ((record.income - 75000) * 0.3);
            }
            else
            {
                record.tax = 11250 + ((record.income - 100000) * 0.4);
            }

            // record.tax = record.income * 0.1;
            fseek(file, -sizeof(struct taxpayer), SEEK_CUR);
            fwrite(&record, sizeof(struct taxpayer), 1, file);
            printf("Record updated successfully.\n");
            return;
        }
    }
    printf("Record not found.\n");
}



void delete_record(FILE *file) {
    char name[30];
    printf("Enter the name of the taxpayer to delete: ");
    scanf("%s", name);
    fseek(file, 0, SEEK_SET);

    struct taxpayer record;
    int found = 0;

    // Create a temporary file
    FILE *temp = fopen("temp.txt", "wb");

    // Read each record from the file and write to the temporary file except for the one to be deleted
    while (fread(&record, sizeof(record), 1, file) == 1) {
        if (strcmp(record.name, name) == 0) {
            found = 1;
        }
         else {
            fwrite(&record, sizeof(record), 1, temp);
        }
    }

    fclose(file);
    fclose(temp);

    if (found) {
        // Delete the original file and rename the temporary file to the original file name
        remove("taxpayers.txt");
        rename("temp.txt", "taxpayers.txt");
        printf("Taxpayer with name %s has been deleted.\n", name);
    } else {
        printf("Taxpayer with name %s not found.\n", name);
        remove("temp.txt");
    }

    // Open the original file for appending
    file = fopen("taxpayers.txt", "ab");
    if (file == NULL) {
        printf("Error opening file.\n");
        exit(1);
    }
}


int main()
{
    FILE *file = fopen("taxpayers.txt", "ab+");
    if (file == NULL)
    {
        printf("Error opening file.\n");
        exit(1);
    }

    int choice;
    do
    {
        printf("\n1. Add New Record\n");
        printf("2. List All Tax Payer along with Income Tax to be paid\n");
        printf("3. Search\n");
        printf("4. Edit\n");
        printf("5. Delete Record\n");
        printf("6. Exit\n");
        printf("Enter your choice: ");
        fflush(stdin);
        scanf("%d", &choice);

        switch (choice)
        {
        case 1:
            add_record(file);
            break;
        case 2:
            show_allrecord(file);
            break;
        case 3:
            search_record(file);
            break;
        case 4:
            edit_record(file);
            break;
        case 5:
            delete_record(file);
            break;
        case 6:
            printf("Exiting...\n");
            break;
        default:
            printf("Invalid choice. Please try again.\n");
            break;
        }
    } while (choice != 6);
    fclose(file);
    return 0;
}

我能够正确运行所有功能，但是一旦我运行 delete_record 功能，我也无法执行其他功能。

请更正此代码，以便我能够从文件中删除特定记录并且还能够执行其他功能

arrays c structure file-handling
1个回答
0
投票

  1. delete_record()
    ：当您重新打开文件时，您会使用不正确的模式“ab”，但应该是“ab+”，因为您打算从中读取。这是一个信号，你应该避免重复自己。

  2. delete_record()
    ：
    file = fopen("taxpayers.txt", "ab+");
    会更新文件的副本，但在函数外没有任何作用。返回新的
    FILE *
    或将参数作为
    FILE **file
    传递。

  3. （留给读者练习）在读取带有 

    scanf()
    的字符串时，始终指定最大字段宽度。

FILE *delete_record(FILE *file) {
    char name[30];
    printf("Enter the name of the taxpayer to delete: ");
    scanf("%s", name);
    fseek(file, 0, SEEK_SET);

    struct taxpayer record;
    int found = 0;

    // Create a temporary file
    FILE *temp = fopen("temp.txt", "wb");

    // Read each record from the file and write to the temporary file except for the one to be deleted
    while (fread(&record, sizeof(record), 1, file) == 1) {
        if (strcmp(record.name, name) == 0) {
            found = 1;
        }
        else {
            fwrite(&record, sizeof(record), 1, temp);
        }
    }
    fclose(file);
    fclose(temp);

    if (found) {
        // Delete the original file and rename the temporary file to the original file name
        remove("taxpayers.txt");
        rename("temp.txt", "taxpayers.txt");
        printf("Taxpayer with name %s has been deleted.\n", name);
    } else {
        printf("Taxpayer with name %s not found.\n", name);
        remove("temp.txt");
    }

    // Open the original file for appending
    file = fopen("taxpayers.txt", "ab+");
    if (file == NULL) {
        printf("Error opening file.\n");
        exit(1);
    }
    return file;
}

// ...

            case 5:
                file = delete_record(file);
                break;

和示例会话：

1. Add New Record
2. List All Tax Payer along with Income Tax to be paid
3. Search
4. Edit
5. Delete Record
6. Exit
Enter your choice: 2
Name                 PancardNo.           Income               TaxPaid               
jane                 23456               Rs.4.00                Rs.0.00               

1. Add New Record
2. List All Tax Payer along with Income Tax to be paid
3. Search
4. Edit
5. Delete Record
6. Exit
Enter your choice: 1
Enter name: bob
Enter 5-digit Pancard_number: 23456
Enter Mobileno: 2
Enter income: 2
Record added successfully.

1. Add New Record
2. List All Tax Payer along with Income Tax to be paid
3. Search
4. Edit
5. Delete Record
6. Exit
Enter your choice: 5
Enter the name of the taxpayer to delete: jane 
Taxpayer with name jane has been deleted.

1. Add New Record
2. List All Tax Payer along with Income Tax to be paid
3. Search
4. Edit
5. Delete Record
6. Exit
Enter your choice: 2
Name                 PancardNo.           Income               TaxPaid               
bob                  23456               Rs.2.00                Rs.0.00
最新问题
© www.soinside.com 2019 - 2024. All rights reserved.