Question

//伙计我的代码有问题，并试图解决这个问题而撕裂我的头发。问题是我正在尝试验证我的代码，因此它不会计算负数。如果任何人可以帮助顺利完成这个程序，我会非常感激。请。

//税务计算器计划的目标是使用C编程计算每个Kudler Fine Food商店（DelMar，Encinitas和La Jolla）的销售税 //标准输入/输出处理

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


//Starting point    
int main ()
{   
//Variables defined
//st = sales tax, tax rated = tr, pa = total purchase amount, sa = purchase amoount

    float fstDelmar;
    float ftrDelmar;
    float fpaDelmar;
    float fstEncinitas;
    float ftrEncinitas;
    float fpaEncinitas;
    float fstLajolla;
    float ftrLajolla;
    float fpaLajolla;
    float fsaPurchaseAmount;
    int fStoreselect;

//Variable initializations for tax rates and purchase amount 
    ftrDelmar = .0725;
    ftrEncinitas = .075;
    ftrLajolla = .0775;
    fsaPurchaseAmount = 0;


//Header & Introduction
    printf("\n***********************************************************************");
    printf("\n*                         Kudler Fine Foods                           *");
    printf("\n*                       Sales Tax Calculator                          *");
    printf("\n*                           Version 3.0                               *");
    printf("\n***********************************************************************\n");


//Ask user to select store.

    printf ("\n                 STORE LOCATION \n");
    printf ("\n                 1) Del Mar \n");
    printf ("\n                 2) Encinitas \n");
    printf ("\n                 3) La Jolla \n");

    printf ("\n Please select the store location (1-3):  \n");
    scanf ("%d", &fStoreselect);    

//Validate store selection.
    while (fStoreselect < 1 || fStoreselect > 3) {
        fflush (fStoreselect);
        printf ("INVALID SELECTION! Please select a valid location (1-3): \n"); 
        scanf ("%d", &fStoreselect);
        }
//Ask user to enter in total purchase amount.

    printf ("\n What was your purchase amount? "); 
    scanf("$%f", &fsaPurchaseAmount); //user enters variable amount


//Validation to ensure that user's enter in purchase amounts using correct format.

    while (fsaPurchaseAmount <= 0.0) 
        {
        fflush(fsaPurchaseAmount);                                          
        printf("\n INVALID SELECTION! Please enter a valid purchase amount greater than zero.\n");
        printf("\n The purchase amount is: $ ");
        scanf("%f", &fsaPurchaseAmount);    
        }

//Calculation of sales tax in dollars for each of the store locations
    fstDelmar = fsaPurchaseAmount * ftrDelmar;
    fstEncinitas = fsaPurchaseAmount * ftrEncinitas;
    fstLajolla = fsaPurchaseAmount * ftrLajolla; 

//Calculation of total sales amount for each of the locations

    fpaDelmar = fsaPurchaseAmount + fstDelmar;
    fpaEncinitas = fsaPurchaseAmount + fstEncinitas;
    fpaLajolla = fsaPurchaseAmount + fstLajolla;

//Displaying sales amount for purchase for each of the different locations

    switch (fStoreselect) {

        case 1: 
    //for Delmar location
        printf("\n       Purchase Amount      Sales Tax     Total Sales Amount ");
        printf("\n       _______________      _________     _________________ ");
        printf("\n            $%.2f              $%.2f            $%.2f",fsaPurchaseAmount, fstDelmar, fpaDelmar);
        break;

        case 2:
    //for Encinitas location
        printf("\n       Purchase Amount      Sales Tax     Total Sales Amount ");
        printf("\n       _______________      _________     _________________ ");
            printf("\n            $%.2f              $%.2f            $%.2f",fsaPurchaseAmount, fstEncinitas, fpaEncinitas);
            break;

            case 3:
        //for La Jolla location
            printf("\n       Purchase Amount      Sales Tax     Total Sales Amount ");
        printf("\n       _______________      _________     _________________ ");
            printf("\n            $%.2f              $%.2f            $%.2f",fsaPurchaseAmount, fstLajolla, fpaLajolla);   
        break; 
        }

    printf("\n Hit the ENTER key to exit program\n");
//Pause the screen and wait for user to hit the ENTER key
    getchar();

//EOF      
}

Answer 1

这一行有错误：

scanf（“ $ ％f”，＆amp; fsaPurchaseAmount）; //用户输入可变金额

它应该是：

scanf（“％f”，＆amp; fsaPurchaseAmount）; //用户输入可变金额

Answer 2

以下是对所呈现代码的一些观察：

不要使用浮点钱。它只会导致悲伤。理想情况下，请咨询会计专业人士。与此同时，以美分为单位进行算术运算，并以美元为单位进行比例显示。
销售税等计算可能可以通过浮点乘法正确完成，但请确保遵守公认的回合整数美分的做法。再次，向会计专业人士寻求建议。
fflush()没有按照您的想法行事。对于为写入而打开的文件描述符（例如stdout），它保证该描述符上的所有输出都已完成。在打印提示后使用，在调用类似scanf()之类的之前使用来读取输入。例如：printf("What is your favorite color? "); fflush(stdout); fgets(color, sizeof(color), stdin);

始终检查scanf()的返回值。它返回成功的转换次数。如果它与格式说明符的数量不匹配，那么只有那些成功的值才会将值写入命名变量。

警惕除scanf()格式字符串中出现的空格以外的文字字符。这些必须与输入文本完全匹配，否则转换将失败。因此像"$%f"这样的格式只与包含文字美元符号的输入相匹配。这可能不是您的用户期望的。格式"%f"对用户来说更容易。如果您想允许可选的美元符号，则scanf()可能不是最佳选择。

程序验证问题。请帮忙！

2 个答案: