Question

下面只是我正在处理的一个简单程序，我需要获取所有printf并在指令中对其进行定义。

#include <stdio.h>
#define name(parameter) printf("......")

main(){
...
}

我该怎么做？

#include <stdio.h>

#define FICA_PERCENTAGE 0.0765
#define HOURS_WORKED(int hours_worked) printf("\nHours Worked:  %d\n", hours_worked)
#define HOURLY_RATE(float hourly_rate) printf("Hourly Rate:  $%5.2f\n", hourly_rate)
#define GROSS_PAY(float gross_pay) printf("Gross PAy:  $%5.2f\n", gross_pay)
#define FICA_DEDUCTION(float fica_deduction) printf("FICA deduction:  $%5.2f\n", fica_deduction)
#define NET_PAY(float net_pay) printf("Net Pay:  $%5.2f\n", net_pay)

main(){

    int hours_worked;
    float hourly_rate, gross_pay, net_pay,fica_deduction;

    printf("Simple Payroll Program: \n");
    printf("-------------------\n");
    printf("Enter the number of hrs workrd: ");
    scanf("%d", &hoursWorked);
    printf("Enter the hourly rte of pay: ");
    scanf("%f", &hourly_rate);

    gross_pay = hoursWorked * hourly_rate;
    fica_deduction = gross_pay * FICA_PERCENTAGE;
    net_pay = gross_pay - fica_deduction;

    HOURS_WORKED;
    HOURLY_RATE;
    GROSS_PAY;
    FICA_DEDUCTION;
    NET_PAY;

    /*printf("\nHours Worked:  %d\n", hoursWorked);
    printf("Hourly Rate:  $%5.2f\n", hourly_rate);
    printf("Gross PAy:  $%5.2f\n", gross_pay);
    printf("FICA deduction:  $%5.2f\n", fica_deduction);
    printf("Net Pay:  $%5.2f\n", net_pay);*/

    return 0;
}

#include <stdio.h>

#define FICA_PERCENTAGE 0.0765
main(){

    int hours_worked;
    float hourly_rate, gross_pay, net_pay,fica_deduction;

    printf("Simple Payroll Program: \n");
    printf("-------------------\n");
    printf("Enter the number of hrs workrd: ");
    scanf("%d", &hoursWorked);
    printf("Enter the hourly rte of pay: ");
    scanf("%f", &hourly_rate);

    gross_pay = hoursWorked * hourly_rate;
    fica_deduction = gross_pay * FICA_PERCENTAGE;
    net_pay = gross_pay - fica_deduction;

    printf("\nHours Worked:  %d\n", hoursWorked);
    printf("Hourly Rate:  $%5.2f\n", hourly_rate);
    printf("Gross PAy:  $%5.2f\n", gross_pay);
    printf("FICA deduction:  $%5.2f\n", fica_deduction);
    printf("Net Pay:  $%5.2f\n", net_pay);

    return 0;
}

Answer 1

宏执行替换，并带有可选的参数替换

#define X yyyy

将用X替换令牌yyyy的出现。

#define X(Y) yyyy Y yyyy

将用X(Foo)替换参数化令牌yyyy Foo yyyy的出现。

以您的第一次printf尝试为例，看来您想要这样做：

#define HOURS_WORKED(Y) \
        printf("\nHours Worked:  %d\n", Y)

然后，您将这样称呼它：

HOURS_WORKED(hoursWorked);

您需要对其他宏和调用进行相应的调整。

Answer 2

这不是宏的好用例。它只会混淆您的代码，并在不需要的地方增加一些复杂性。但是，如果您致力于此，则需要进行一些更改。

首先，宏参数没有类型：

#define HOURS_WORKED(hours_worked) printf("\nHours Worked:  %d\n", hours_worked)

第二，在调用宏时，还需要提供参数：

HOURS_WORKED(hoursWorked);

请记住，类似函数的宏不是函数-它们只是文本替换。不评估宏参数，它们只是在适当位置扩展。也就是说，如果您将HOURS_WORKED调用为

HOURS_WORKED(n * 40);

然后它将扩展为

printf("\nHours Worked:  %d\n", n * 40)

为避免优先级和解析问题，将宏参数包装在parens中通常是一个好主意：

#define HOURS_WORKED(hours_worked) printf("\nHours worked: %d\n", (hours_worked) );

有什么方法可以使用#define指令定义printf函数？

2 个答案: