Question

我在C中制作了一个程序，用尽可能少的账单来计算要提取的资金。一切都按预期工作，但出于某种原因，返还的美元钞票数量几乎总是一个。例如，如果我输入我要撤回549，它会给5美元钞票，两个二十，一个五，但是三美元而不是四美元，总计548。如果我想要320，它会给 - 1美元回来。我不确定该程序有什么问题 - 我检查了数学和所有内容，并在不同的编译器上进行了尝试。任何帮助将不胜感激。

#include <stdio.h>

int main()
{
    int amountToWithdraw = 0;
    int hundredsWithdrawn = 0;
    int fiftysWithdrawn = 0;
    int twentysWithdrawn = 0;;
    int tensWithdrawn= 0;
    int fivesWithdrawn= 0;
    int onesWithdrawn= 0;

    printf ("Please enter the amount of money you wish to withdraw:");
    scanf ("%d", &amountToWithdraw);

    hundredsWithdrawn = amountToWithdraw / 100;
    amountToWithdraw = amountToWithdraw % 100;
    fiftysWithdrawn = (amountToWithdraw - hundredsWithdrawn) / 50;
    amountToWithdraw = amountToWithdraw % 50;
    twentysWithdrawn = (amountToWithdraw - fiftysWithdrawn) / 20;
    amountToWithdraw = amountToWithdraw % 20;
    tensWithdrawn = (amountToWithdraw - twentysWithdrawn) / 10;
    amountToWithdraw = amountToWithdraw % 10;
    fivesWithdrawn = (amountToWithdraw - tensWithdrawn) / 5; 
    amountToWithdraw = amountToWithdraw % 5;
    onesWithdrawn = (amountToWithdraw - fivesWithdrawn) / 1;

    printf ("You received %d hundred(s)", hundredsWithdrawn);
    printf ("You received %d fifty(s)", fiftysWithdrawn);
    printf ("You received %d twenty(s)",twentysWithdrawn);
    printf ("You received %d ten(s)", tensWithdrawn);
    printf ("You received %d five(s)", fivesWithdrawn);
    printf ("You received %d one(s)", onesWithdrawn);

    return 0;
}

Answer 1

我不喜欢使用StackOverflow作为“修复我的代码”服务，甚至没有阅读代码开始......

但我很想知道有多少错误，并在此过程中修复了它。

这应该合理得当：

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

int main()
{
    int money = 0;
    int hundreds = 0;
    int fiftys = 0;
    int twentys = 0;
    int tens = 0;
    int fives = 0;
    int ones = 0;

    printf("Please enter the amount of money you wish to withdraw:");
    scanf("%d", &money);

    hundreds = money / 100;
    money %= 100;
    fiftys = money / 50;
    money %= 50;
    twentys = money / 20;
    money %= 20;
    tens = money / 10;
    money %= 10;
    fives = money / 5;
    money %= 5;
    ones = money / 1;

    printf("You received %d hundred(s)\n", hundreds);
    printf("You received %d fifty(s)\n", fiftys);
    printf("You received %d twenty(s)\n",twentys);
    printf("You received %d ten(s)\n", tens);
    printf("You received %d five(s)\n", fives);
    printf("You received %d one(s)\n", ones);

    return 0;
}

完成的更改：

为scanf()
修正了数学
为printf
使变量名更具可读性

Answer 2

您的程序逻辑错误。而不是：

fiftysWithdrawn = (amountToWithdraw - hundredsWithdrawn) / 50;

它应该是：

fiftysWithdrawn = amountToWithdraw / 50;

和所有其他类似的线类似。

您已经丢弃了数百个（通过执行amountToWithdraw = amountToWithdraw % 100;），因此您不需要将它们计入剩余的计算中。

549的“关闭一个”错误是因为在最后一步中onesWithdrawn = (4 - 1) / 1;提供3，实际上它应该是4。 1来自fivesWithdrawn的虚假使用。因此，我希望您找到以5,6,7,8,9结尾的任何金额的off-by-one错误，而不是其他金额。

其他音符不会显示错误，因为误差量小于您所划分的误差，例如再次使用549，您可以(49 - 5) / 20获取二十位数，但这与正确的版本49 / 20给出相同的答案。

顺便说一下，您可能希望使用%=运算符来使您的代码可读;它的工作方式是A %= B表示A = A % B。并在printf的末尾使用\n。

提款计算器总是关闭一美元钞票的金额

2 个答案:

完成的更改：