c - 枚举和一个以字符串形式返回月份名称的函数

Question

这是练习:

Write a function called monthName() that takes as its argument a value of type enum month (as defined in this chapter) and returns a pointer to a character string containing the name of the month. In this way, you can display the value of an enum month variable with a statement such as:

printf("%s\n", monthName(aMonth));

我编写了我的版本并获得了预期的输出。但是，我确信必须有更好的方法来实现这一点，而不必每个月都使用一个 case 的 switch 语句。我怎样才能用更好的设计来编写这个函数？

#include <stdio.h>

enum month { January = 1, February, March, April, May, June, 
        July, August, September, October, November, December };

char *monthName(enum month m){
    switch (m) {
        case January:
            return "January";
            break;
        case February:
            return "February";
            break;
        case March:
            return "March";
            break;
        case April:
            return "April";
            break;
        case May:
            return "May";
            break;
        case June:
            return "June";
            break;
        case July:
            return "July";
            break;
        case August:
            return "August";
            break;
        case September:
            return "September";
            break;
        case October:
            return "October";
            break;
        case November:
            return "November";
            break;
        case December:
            return "December";
            break;
        default:
            return "Not a valid month";
    }
}

int main(void)
{
    enum month aMonth = 1;

    printf("%s\n", monthName(aMonth));

    aMonth = 2;
    printf("%s\n", monthName(aMonth));

    aMonth = 6;
    printf("%s\n", monthName(aMonth));

    return 0;
}

Answer 1

您可以使用一个简单的查找表，因为枚举以 1 开头:

#include <stdio.h>

enum month { January = 1, February, March, April, May, June, 
        July, August, September, October, November, December };

const char *months_str[] = {
    "January", "February", "March", "April", "May", "June", "July",
    "August", "September", "October", "November", "December", NULL
};

const char *monthName(enum month m) {
    if(m < January || m > December)
        return "Invalid month";

    return months_str[m-1];
}

int main(void)
{
    enum month aMonth = 1;

    printf("%s\n", monthName(aMonth));

    aMonth = 2;
    printf("%s\n", monthName(aMonth));

    aMonth = 6;
    printf("%s\n", monthName(aMonth));

    return 0;
}