月末日取得【C言語】

うるう年の計算が必要な場合はつまり月末の日付が知りたいときなので、
うるう年判定関数を利用して、その月の月末日を取得しましょう。

　When you would like to know whether it is leap year or not,
you would like to know the last day of month.
Get the day.

　関連記事：うるう年判定【C言語】

#define TRUE   0
#define FALSE -1

// is leap or not
int IsLeapYear(int year)
{
    if (((year % 4 == 0) && (year % 100 != 0)) || year % 400 == 0) {
        return TRUE;
    } else {
        return FALSE;
    }
}

// get the last day of month
int GetLastDay(int year, int month)
{
    int leap;
    int lmdays[] = {31,29,31,30,31,30,31,31,30,31,30,31};
    int mdays[]  = {31,28,31,30,31,30,31,31,30,31,30,31};

    leap = IsLeapYear(year);
    // leap year
    if (leap == TRUE) {
        return lmdays[month - 1];
    // no_leap year
    } else {
        return mdays[month - 1];
    }
}