如何用C语言从TXT文件计算月度及年度支出？

我正在编写一个C语言读写程序，但不清楚如何实现月度和年度支出统计操作，请求帮助。

示例TXT文件内容 #

Jaka 2022 12  10 50000
Juki 2020 10  12 750000
Jaka 12 10  10 4000

现有代码 #

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

void input();
void count();
void monthly_expenditure();

int main()
{
    int choice;
    do
    {
        printf("====================================MENU====================================\n");
        printf("1. Input Data\n");
        printf("2. count expenditure\n");
        printf("3. monthly expenditure\n");
        printf("4. exit\n");
        printf("choice : ");
        scanf("%d", &choice);
        switch (choice)
        {
        case 1:
            input();
            getchar();
            break;
        case 2:
            count();
            getchar();
            break;
        case 3:
            monthly_expenditure();
            getchar();
            break;
        case 4:
            printf("thank you\n");
            getchar();
            break;
        default:
            printf("error\n");
            break;
        }
    } while (choice != 4);
    return 0;
}

void input()
{
    FILE *fp;
    char name[100], year[100], month[100], date[100], money[100];
    fp = fopen("data.txt", "a");

    printf("Input name : ");
    scanf("%s", name);
    printf("Input year : ");
    scanf("%s", year);
    printf("Input month : ");
    scanf("%s", month);
    printf("Input date : ");
    scanf("%s", date);
    printf("Input money : ");
    scanf("%s", money);
    fprintf(fp, "%s %s %s  %s %s\n", name, year, month, date, money);
    fclose(fp);
}

void count()
{
    FILE *fp;
    char name[100], year[100], month[100], date[100], money[100];
    int total = 0;
    fp = fopen("data.txt", "r");

    while (fscanf(fp, "%s %s %s %s %s", name, year, month, date, money) != EOF)
    {
        total += atoi(money);
    }
    printf("Total expenditure : %d\n", total);
    fclose(fp);
}

void monthly_expenditure(){

}
void year_expenditure(){

}

解决方案 #

1. 先修复数据输入的合法性问题 #

示例数据里存在年份输入错误（比如Jaka 12 10 10 4000中的年份仅2位），可以在input函数中添加基础校验，确保年份、月份、金额等数据符合逻辑：

void input()
{
    FILE *fp;
    char name[100];
    int year, month, date, money;
    fp = fopen("data.txt", "a");
    if (!fp) {
        perror("Failed to open file");
        return;
    }

    printf("Input name : ");
    scanf("%s", name);
    
    // 校验4位年份
    do {
        printf("Input year (4 digits): ");
        if (scanf("%d", &year) != 1 || year < 1900 || year > 2100) {
            printf("Invalid year! Enter 4-digit number between 1900-2100.\n");
            while (getchar() != '\n'); // 清除输入缓冲区垃圾
        }
    } while (year < 1900 || year > 2100);
    
    // 校验1-12月份
    do {
        printf("Input month (1-12): ");
        if (scanf("%d", &month) != 1 || month < 1 || month > 12) {
            printf("Invalid month! Enter number between 1-12.\n");
            while (getchar() != '\n');
        }
    } while (month < 1 || month > 12);
    
    // 校验1-31日期
    do {
        printf("Input date (1-31): ");
        if (scanf("%d", &date) != 1 || date < 1 || date > 31) {
            printf("Invalid date! Enter number between 1-31.\n");
            while (getchar() != '\n');
        }
    } while (date < 1 || date > 31);
    
    // 校验正数金额
    do {
        printf("Input money (positive number): ");
        if (scanf("%d", &money) != 1 || money <= 0) {
            printf("Invalid money! Enter positive number.\n");
            while (getchar() != '\n');
        }
    } while (money <= 0);

    fprintf(fp, "%s %d %d  %d %d\n", name, year, month, date, money);
    fclose(fp);
}

2. 实现月度支出统计函数 #

让用户输入目标年月，遍历文件累加对应记录的金额：

void monthly_expenditure()
{
    FILE *fp;
    char name[100];
    int target_year, target_month;
    int year, month, date, money;
    int total = 0;

    printf("Enter year to query: ");
    scanf("%d", &target_year);
    printf("Enter month to query: ");
    scanf("%d", &target_month);

    fp = fopen("data.txt", "r");
    if (!fp) {
        perror("Failed to open file");
        return;
    }

    while (fscanf(fp, "%s %d %d %d %d", name, &year, &month, &date, &money) != EOF) {
        if (year == target_year && month == target_month) {
            total += money;
        }
    }

    printf("Total expenditure for %d-%d: %d\n", target_year, target_month, total);
    fclose(fp);
}

3. 实现年度支出统计函数 #

类似月度统计，用户输入目标年份后累加对应记录：

void year_expenditure()
{
    FILE *fp;
    char name[100];
    int target_year;
    int year, month, date, money;
    int total = 0;

    printf("Enter year to query: ");
    scanf("%d", &target_year);

    fp = fopen("data.txt", "r");
    if (!fp) {
        perror("Failed to open file");
        return;
    }

    while (fscanf(fp, "%s %d %d %d %d", name, &year, &month, &date, &money) != EOF) {
        if (year == target_year) {
            total += money;
        }
    }

    printf("Total expenditure for %d: %d\n", target_year, total);
    fclose(fp);
}

4. 更新主菜单 #

添加年度统计选项，调整main函数的菜单和分支：

int main()
{
    int choice;
    do
    {
        printf("====================================MENU====================================\n");
        printf("1. Input Data\n");
        printf("2. Count Total Expenditure\n");
        printf("3. Monthly Expenditure\n");
        printf("4. Yearly Expenditure\n");
        printf("5. Exit\n");
        printf("choice : ");
        scanf("%d", &choice);
        switch (choice)
        {
        case 1:
            input();
            getchar();
            break;
        case 2:
            count();
            getchar();
            break;
        case 3:
            monthly_expenditure();
            getchar();
            break;
        case 4:
            year_expenditure();
            getchar();
            break;
        case 5:
            printf("thank you\n");
            getchar();
            break;
        default:
            printf("error\n");
            break;
        }
    } while (choice != 5);
    return 0;
}

额外优化方向 #

• 可以统计每个用户的月度/年度支出，用结构体或数组存储多用户统计结果
• 封装重复的文件操作逻辑，减少代码冗余
• 处理闰年、不同月份天数的精确日期校验

内容的提问来源于stack exchange，提问作者rotibakar