扫描字符并将 Switch 语句与 If 语句相结合？开关（时间）

Question

我写的代码：

#include<stdio.h>
int main()
{
    int yos;
    double salary;
    char time;

    printf("Please enter your employee status, 'P' for Fulltime and 'P' for Parttime: \n");
    scanf_s("%c", &time);
    printf("Please enter your year of service: \n");
    scanf_s("%d", &yos);
    printf("Please enter your current salary: \n");
    scanf_s("%lf", &salary);

    switch (time)
    {
    case 'F':
    case 'f':
        if (yos >= 5)
        {
            salary = (salary*5.0 / 100.0) + salary;
            printf("\nYour new salary is %.2lf", salary);
        }
        else if (yos < 5 )
        {
            salary = (salary*4.0 / 100.0) + salary;
            printf("\nYour new salary is %.2lf", salary);   
        }
        break;

    case 'P':
    case 'p':
        if (yos >= 5)
        {
            salary = (salary*3.0 / 100.0) + salary;
            printf("\nYour new salary is %.2lf", salary);
        }
        else if (yos < 5 )
        {
            salary = (salary*2.5 / 100.0) + salary;
            printf("\nYour new salary is %.2lf", salary);       
        }
        break;
    default:
        printf("Please put the details correctly\n");
    }

    return(0);
}

由于某种原因，当我运行程序时，我得到以下输出：

Please enter your employee status, 'P' for Fulltime and 'P' for Parttime:
F
Please enter your year of service:
6
Please enter your current salary:
200
Please put the details correctly
Press any key to continue

是否因为无法扫描字符而出现此问题？我什至尝试过分隔 %c。我也不认为放置 %s 或 %[^\n] 会有任何用处，因为它只涉及 1 个字符。有人帮帮我吗？

我还尝试了不同的代码，这些代码只涉及 if 语句，例如：

#include<stdio.h>
int main()
{
    int yos;
    double salary;
    char time;

    printf("Please enter your employee status, 'P' for Fulltime and 'P' for Parttime: \n");
    scanf_s("%c", &time);
    printf("Please enter your year of service: \n");
    scanf_s("%d", &yos);
    printf("Please enter your current salary: \n");
    scanf_s("%lf", &salary);

    if (char time == 'F' && yos >= 5)
    {
        salary = (salary*5.0 / 100.0) + salary;
        printf("\nYour new salary is %.2lf", salary);
    }

    else if (char time == 'F' && yos < 5)
    {
        salary = (salary*4.0 / 100.0) + salary;
        printf("\nYour new salary is %.2lf", salary);
    }

    if (char time == 'P' && yos >= 5)
    {
        salary = (salary*3.0 / 100.0) + salary;
        printf("\nYour new salary is %.2lf", salary);
    }

    else if (char time == 'P' && yos < 5)
    {
        salary == (salary*2.5 / 100.0) + salary;
        printf("\nYour new salary is %.2lf", salary);
    }
    return(0);
}

但是，这个是给的

error c2143 missing ',' before '==' at line 15, 21, 27...

还有这个：

Warning 11  warning C4553: '==' : operator has no effect; did you intend '='?   

Answer 1

当使用%c 格式说明符时，您需要提供一个附加参数来指定要读取的字符数。来自MSDN page for scanf_s：

与scanf 和wscanf 不同，scanf_s 和wscanf_s 需要缓冲区大小 为 c、C、s、S 或字符串类型的所有输入参数指定 包含在 [] 中的控制集。以字符为单位的缓冲区大小为 紧跟在指向的指针之后作为附加参数传递 缓冲区或变量。

...

在字符的情况下，单个字符可以如下读取：

char c;

scanf_s("%c", &c, 1);

因为您没有传入所需数量的参数，所以您调用undefined behavior。

所以当你在time阅读时，这样做：

scanf_s("%c", &time, 1);

另外，在您的第二个示例中，这是无效的语法：

if (char time == 'F' && yos >= 5)

在这里去掉char关键字。

Answer 2

我选择使用scanf 而不是scanf_s，而且我更喜欢在switch 语句中使用枚举和整数。您的代码的以下编辑对我有用；

#include<stdio.h>
int main()
{
    int yos;
    double salary;
    char time;

    printf("Please enter your employee status, 'F' for Fulltime and 'P' for Parttime: \n");
    scanf("%c", &time);
    printf("Please enter your year of service: \n");
    scanf("%d", &yos);
    printf("Please enter your current salary: \n");
    scanf("%lf", &salary);

    int status;
    if(time=='F'||time=='f')
        status = 1;
    if(time=='P'||time=='p')
        status = 2;
    switch (status)
    {
    case 1:
        if (yos >= 5)
        {
            salary = (salary*5.0 / 100.0) + salary;
            printf("\nYour new salary is %.2lf", salary);
        }
        else if (yos < 5 )
        {
            salary = (salary*4.0 / 100.0) + salary;
            printf("\nYour new salary is %.2lf", salary);
        }
        break;

    case 2:
        if (yos >= 5)
        {
            salary = (salary*3.0 / 100.0) + salary;
            printf("\nYour new salary is %.2lf", salary);
        }
        else if (yos < 5 )
        {
            salary = (salary*2.5 / 100.0) + salary;
            printf("\nYour new salary is %.2lf", salary);
        }
        break;
    default:
        printf("Please put the details correctly\n");
    }

    return(0);
}

Answer 3

scanf_s 是 Microsoft 特定的，您使用的是必须使用它吗？如果我尝试使用scanf 和gcc 编译器，那么第一个版本的程序似乎可以工作，并且在程序运行时不会打印默认语句。

#include<stdio.h>

int main() {
    int yos;
    double salary;
    char time;

    printf("Please enter your employee status, 'F' for Fulltime and 'P' for Parttime: \n");
    scanf("%c", &time);
    printf("Please enter your year of service: \n");
    scanf("%d", &yos);
    printf("Please enter your current salary: \n");
    scanf("%lf", &salary);

    switch (time) {
        case 'F':
        case 'f':
            if (yos >= 5) {
                salary = (salary * 5.0 / 100.0) + salary;
                printf("\nYour new salary is %.2lf", salary);
            }
            else if (yos < 5) {
                salary = (salary * 4.0 / 100.0) + salary;
                printf("\nYour new salary is %.2lf", salary);
            }
            break;

        case 'P':
        case 'p':
            if (yos >= 5) {
                salary = (salary * 3.0 / 100.0) + salary;
                printf("\nYour new salary is %.2lf", salary);
            }
            else if (yos < 5) {
                salary = (salary * 2.5 / 100.0) + salary;
                printf("\nYour new salary is %.2lf", salary);
            }
            break;
        default:
            printf("Please put the details correctly\n");
    }

    return (0);
} 

测试

Please enter your employee status, 'F' for Fulltime and 'P' for Parttime: 
F
Please enter your year of service: 
6
Please enter your current salary: 
200

Your new salary is 210.00