c - 开关盒菜单

Question

我正在尝试制作一个程序，向用户提示这样一个选项菜单

*****************************************************************
Enter the number corresponding to the desired pay rate or action:
1) $8.75/hr 2) $9.33/hr
3) $10.00/hr 4) $11.20/hr
5) quit
*****************************************************************

然后根据工资率计算净工资、毛工资和税金。我已经完成了所有的工资率，但实际的费率菜单给我带来了问题。如果用户输入 5，它应该退出，如果输入任何其他内容和 1 到 5，然后再循环并再次询问正确的选择。如果输入不是 1 到 5，我在回收时遇到问题。

#include "stdafx.h"
#include "stdio.h"
#include "stdlib.h"
#include "ctype.h"
#define HOURLY0   8.75
#define HOURLY1  9.33
#define HOURLY2  10
#define HOURLY3  11.20
#define TAXRATE  .15
#define TAXRATE2 .20
#define TAXRATE3 .25
#define OVERTIME 15


int _tmain(int argc, _TCHAR* argv[])
{
    float hours, grossPay = 0, netPay, tax = 0, tax3 = 0,hourly;
    int menu = 0,wrong =1;
    char quit;

    printf("Enter the number corresponding to the desired pay rate or action : \n\n1) $8.75/hr          2) $9.33/hr \n3) $10.00/hr         4) $11.20/hr \n5) quit\n\n");
    scanf_s("%d", &menu);
        while (menu != 5 )
        {
            do
            {
                switch (menu)
                {
                case 1:
                    hourly = HOURLY0;
                    break;
                case 2:
                    hourly = HOURLY1;
                    break;
                case 3:
                    hourly = HOURLY2;
                    break;
                case 4:
                    hourly = HOURLY3;
                    break;
                default:
                    printf("Enter right choice from 1 to 5 only\n");
                    printf("Enter the number corresponding to the desired pay rate or action : \n\n1) $8.75/hr          2) $9.33/hr \n3) $10.00/hr         4) $11.20/hr \n5) quit\n\n");
                    scanf_s("%d", &menu);
                    wrong;
                    break;
                }
            } while (!wrong);/* HOW CAN I MAKE IT TO RECYCLE IF INPUT IS OTHER THAN 1-5*/
            printf("\nEnter hours worked in the week: ");
            scanf_s("%f", &hours);

            if (hours > 40)
            {
                grossPay = (40 * hourly) + ((hours - 40) * OVERTIME);

                if (grossPay <= 300)
                {
                    tax = grossPay * TAXRATE;
                }
                if (grossPay > 300 && grossPay < 450)
                {
                    tax = (300 * TAXRATE) + ((grossPay - 300)*TAXRATE2);
                }
                if (grossPay > 450)
                {
                    tax3 = grossPay - 450;
                    tax = (300 * TAXRATE) + ((grossPay - 300 - tax3)*TAXRATE2) + ((grossPay - 300 - 150)*TAXRATE3);
                }

            }
            else if (hours < 40)
            {
                grossPay = (hours * hourly);

                if (grossPay <= 300)
                {
                    tax = grossPay * TAXRATE;
                }

                if (grossPay > 300 && grossPay < 450)
                {
                    tax = (300 * TAXRATE) + ((grossPay - 300)*TAXRATE2);
                }
                if (grossPay > 450)
                {
                    tax3 = grossPay - 450;
                    tax = (300 * TAXRATE) + ((grossPay - 300 - tax3)*TAXRATE2) + ((grossPay - 300 - 150)*TAXRATE3);
                }
            }
            netPay = grossPay - tax;
            printf("\nGross Pay : %2.3f\nTax: %13.3f\nNet Pay: %10.3f\n\n", grossPay, tax, netPay);
            system("cls");
            printf("Enter the number corresponding to the desired pay rate or action : \n\n1) $8.75/hr          2) $9.33/hr \n3) $10.00/hr         4) $11.20/hr \n5) quit\n\n");
            scanf_s("%d", &menu);
        }
    system("pause");
    return 0;
}

Answer 1

改进代码的一种方法是将用户输入处理移到子例程中。这样一来，所有困惑的错误处理都进入了子例程，main 只需处理有效输入。

在下面的代码中，GetUserInput 函数将永远循环，直到用户输入有效数字、文件结束或 scanf 发生错误>。 GetUserInput 的返回值只能是 1 到 5 之间的值，因此 main 不需要处理任何意外值。

int GetUserInput( void )
{
    int menu;

    for (;;)
    {
        menu = 0;
        printf("Enter the number corresponding to the desired pay rate or action : \n\n1) $8.75/hr          2) $9.33/hr \n3) $10.00/hr         4) $11.20/hr \n5) quit\n\n");
        if ( scanf( "%d", &menu ) != 1 )
            exit( 1 );

        if ( menu >= 1 && menu <= 5 )
            return menu;

        printf( "Enter right choice from 1 to 5 only\n" );
    }
}

int main( void )
{
    int menu = 0;

    while ( menu != 5 )
    {
        menu = GetUserInput();
        switch ( menu )
        {
            case 1:  printf( "\n*** You selected 1 ***\n\n" ); break;
            case 2:  printf( "\n*** You selected 2 ***\n\n" ); break;
            case 3:  printf( "\n*** You selected 3 ***\n\n" ); break;
            case 4:  printf( "\n*** You selected 4 ***\n\n" ); break;
            case 5:  printf( "Bye\n" ); break;
        }
    }
}