除世纪年份(以00结尾的年份)外，年可精确地除以4。只有将世纪完全除以400，世纪年才是a年。
例如，
- 1999年不是a年
- 2000年是a年
- 2004年是a年
检查Le年的程序
#include
int main() {
int year;
printf("Enter a year: ");
scanf("%d", &year);
// leap year if perfectly visible by 400
if (year % 400 == 0) {
printf("%d is a leap year.", year);
}
// not a leap year if visible by 100
// but not divisible by 400
else if (year % 100 == 0) {
printf("%d is not a leap year.", year);
}
// leap year if not divisible by 100
// but divisible by 4
else if (year % 4 == 0) {
printf("%d is a leap year.", year);
}
// all other years are not leap year
else {
printf("%d is not a leap year.", year);
}
return 0;
} 输出1
Enter a year: 1900
1900 is not a leap year.
输出2
Enter a year: 2012
2012 is a leap year.