c - 如何在 C 中更改月份日期时使代码重复自身？

Question

我已经完成了这段代码，并且我做了一个循环，我的代码将从头开始重新启动，但是我希望程序在更改月份日期的同时重新启动，并询问用户他们想要多少个月，以便程序将运行一定次数，因为我添加了 1 月作为第一个月。

#include<stdio.h>
#include<stdlib.h>
float twag(float amount,float rate)
{
    float si;
    si = (amount * rate) / 100;
    return si;
}

float twag2(float amount,float rate)
{
    float er;
    er = twag(amount, rate) + amount;
    return er;
}

int main() 
{
    char answer;
    do {
        float amount;
        float rate;
        float si;
        float er;

        printf("Month1\n");

        printf("\nEnter intial deposit : ");
        scanf("%f", &amount);

        printf("\nEnter Rate of Interest : ");
        scanf("%f", &rate);

        printf("\nSimple Interest : %.2f \n", twag(amount,rate));

        printf("\nEnd Payment: %.2f \n",twag2(amount,rate));

        if (amount <= 100)
            printf("interest rate should be 10%%\n");

        else if (amount <= 200)
            printf("interest rate should be 50%%\n");

        else if (amount <= 500)
            printf("interest rate should be 80%%\n");

        else if (amount >= 500)
            printf("interest rate should be 90%%\n");
        system("PAUSE");


        printf("\nPress Y to continue to the second month or Press any Key To 
        Exit");
        scanf(" %c", &answer); // 
    }
     while (answer == 'y' || answer == 'Y');

    return 0;
}

Answer 1

假设您要应用每月利息，您至少需要保留从今天开始的当前月份和年份的记录，因此实现这一点的方法是使用本地时间

void get_date(int *month, int *day, int *year)
{
    struct tm *current;
    time_t timenow;
    time(&timenow);
    current = localtime(&timenow);
    *month = current->tm_mon+1;
    *day = current->tm_mday;
    *year = current->tm_year+1900;
}

我建议你 read here 为什么 system("PAUSE") 不好，除此之外，您在循环内定义了循环变量，这意味着它们将在每次循环时重置，以及您的兴趣在循环期间应保持不变，因此您的代码应如下所示

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

float twag(float amount,float rate);
float twag2(float amount,float rate);
void get_date(int *month, int *day, int *year);

int main() 
{
    char answer;
    float amount, rate, si, er;
    int day, month, year;

    printf("\nEnter intial deposit : ");
    scanf("%f", &amount);

    printf("\nEnter Rate of Interest : ");
    scanf("%f", &rate);

    get_date(&month, &day, &year);

    do
    {
        // increment date by 1 month
        if (++month > 12) month=1, year++;

        printf("\nDate %d/%d/%d \n", day,month,year);
        printf("\nSimple Interest : %.2f \n", twag(amount,rate));
        printf("\nEnd Payment: %.2f \n",twag2(amount,rate));
        amount = twag2(amount,rate);    

        printf("\nPress Y to continue to the next month or Press any Key To Exit");
        scanf("%c", &answer);
    }
    while (answer == 'y' || answer == 'Y');

    return 0;
}