コード
#include <stdio.h>
typedef struct {
int y;
int m;
int d;
} Date;
Date DateOf(int y, int m, int d);
Date After(Date x, int n);
Date Before(Date x, int n);
int isleap(int year);
int main(void)
{
int y, m, d, a, b;
Date test_day;
Date after_day;
y = 2018;
m = 9;
d = 20;
printf("日付を何日にしますか？：");
scanf("%d", &a);
test_day = DateOf(y, m, d);
after_day = After(test_day, a);
printf("%d年%d月%d日ですね。\n", test_day.y, test_day.m, test_day.d);
printf("--- 日付を進めると ---\n");
printf("%d年%d月%d日ですね。\n", after_day.y, after_day.m, after_day.d);
return 0;
}
Date DateOf(int y, int m, int d)
{
Date today;
today.y = y;
today.m = m;
today.d = d;
return today;
}
Date After(Date x, int n)
{
int uru_flg;
x.d += n;
uru_flg = isleap(x.y);
if(x.m == 1 || x.m == 3 || x.m == 5 || x.m == 7 || x.m == 8 || x.m == 10 || x.m == 12)
{
if(x.d > 31){
x.d = x.d - 31;
x.m += 1;
}
}else if(x.m == 4 || x.m == 6 || x.m == 9 || x.m == 11){
if(x.d > 30){
x.d = x.d - 30;
x.m += 1;
}
}else if(x.m == 2){
if(uru_flg == 0){
if(x.d > 28){
x.d = x.d - 28;
x.m += 1;
}
}else if(uru_flg == 1){
if(x.d > 29){
x.d = x.d - 29;
x.m += 1;
}
}
}
if(x.m == 13){
x.y += 1;
x.m = 1;
}
return x;
}
int isleap(int year)
{
}
メモ
+200日等の大きい数字に対する対応部分が未完成。
恐らくwhile文でx.d <= 31になるまでループを回し続けるように改修を加えれば実現できそうだ。
*1:year % 4 == 0) && (year % 100 != 0
