days_in_month

Conditions and loops

Your mission

Write a function that returns how many days the month month of the year year has, and -1 when month is not a month number.

See it in action

days_in_month(2024, 1)

Expected result

Your checklist

For your own tracking. Tests grade your code.

month is a month number: 1 is January, 12 is December. year is the calendar year that month falls in.
January, March, May, July, August, October and December have 31 days.
April, June, September and November have 30 days.
February has 29 days in a leap year and 28 days otherwise, which is the only place year is used.
A year is a leap year when it divides by 4, except that a year dividing by 100 is not one, unless it also divides by 400. 2024 is a leap year, 1900 is not, 2000 is.
Outside February the year is irrelevant. April has 30 days in 2000 and 30 days in 2001.
Return -1 when month is below 1 or above 12. That covers 0, 13 and every negative value.

More examples

days_in_month(2024, 2)

Expected result

days_in_month(1900, 2)

Expected result

days_in_month(2000, 2)

Expected result

days_in_month(2024, 9)

Expected result

days_in_month(1999, 13)

Expected result

-1

Constraints

Expected files

days_in_month.c

Allowed functions

None. Write every helper yourself.

Tests

Run the tests to grade your code

Build your code, then check each test here. Open a result to inspect its output.

Build

01January has 31 daysWaiting

02February 2024 has 29 daysWaiting

03February 2023 has 28 daysWaiting

041900 divides by 100 and is not a leap yearWaiting

052000 divides by 400 and is a leap yearWaiting

061600 divides by 400 and is a leap yearWaiting

071800 divides by 100 and is not a leap yearWaiting

082100 divides by 100 and is not a leap yearWaiting

09February 1996 has 29 daysWaiting

10March has 31 daysWaiting

11April has 30 daysWaiting

12May has 31 daysWaiting

13June has 30 daysWaiting

14July and August both have 31 daysWaiting

15September has 30 daysWaiting

16October has 31 daysWaiting

17November has 30 daysWaiting

18December has 31 daysWaiting

19A leap year does not change AprilWaiting

20Every month of a leap yearWaiting

21Every month of a century yearWaiting

22Month 0 is invalidWaiting

23Month 13 is invalidWaiting

24A negative month is invalidWaiting

25A month far above 12 is invalidWaiting

26The extreme int values are invalid monthsWaiting

days_in_month

Your mission

Write a function that returns how many days the month month of the year year has, and -1 when month is not a month number.

See it in action

days_in_month(2024, 1)

Expected result

Your checklist

For your own tracking. Tests grade your code.

month is a month number: 1 is January, 12 is December. year is the calendar year that month falls in.
January, March, May, July, August, October and December have 31 days.
April, June, September and November have 30 days.
February has 29 days in a leap year and 28 days otherwise, which is the only place year is used.
A year is a leap year when it divides by 4, except that a year dividing by 100 is not one, unless it also divides by 400. 2024 is a leap year, 1900 is not, 2000 is.
Outside February the year is irrelevant. April has 30 days in 2000 and 30 days in 2001.
Return -1 when month is below 1 or above 12. That covers 0, 13 and every negative value.

More examples

days_in_month(2024, 2)

Expected result

days_in_month(1900, 2)

Expected result

days_in_month(2000, 2)

Expected result

days_in_month(2024, 9)

Expected result

days_in_month(1999, 13)

Expected result

-1

Constraints

Expected files

days_in_month.c

Allowed functions

None. Write every helper yourself.

days_in_month

Conditions and loops

Your mission

Write a function that returns how many days the month month of the year year has, and -1 when month is not a month number.

See it in action

days_in_month(2024, 1)

Expected result

Your checklist

For your own tracking. Tests grade your code.

month is a month number: 1 is January, 12 is December. year is the calendar year that month falls in.
January, March, May, July, August, October and December have 31 days.
April, June, September and November have 30 days.
February has 29 days in a leap year and 28 days otherwise, which is the only place year is used.
A year is a leap year when it divides by 4, except that a year dividing by 100 is not one, unless it also divides by 400. 2024 is a leap year, 1900 is not, 2000 is.
Outside February the year is irrelevant. April has 30 days in 2000 and 30 days in 2001.
Return -1 when month is below 1 or above 12. That covers 0, 13 and every negative value.

More examples

days_in_month(2024, 2)

Expected result

days_in_month(1900, 2)

Expected result

days_in_month(2000, 2)

Expected result

days_in_month(2024, 9)

Expected result

days_in_month(1999, 13)

Expected result

-1

Constraints

Expected files

days_in_month.c

Allowed functions

None. Write every helper yourself.

Tests

Run the tests to grade your code

Build your code, then check each test here. Open a result to inspect its output.

Build

01January has 31 daysWaiting

02February 2024 has 29 daysWaiting

03February 2023 has 28 daysWaiting

041900 divides by 100 and is not a leap yearWaiting

052000 divides by 400 and is a leap yearWaiting

061600 divides by 400 and is a leap yearWaiting

071800 divides by 100 and is not a leap yearWaiting

082100 divides by 100 and is not a leap yearWaiting

09February 1996 has 29 daysWaiting

10March has 31 daysWaiting

11April has 30 daysWaiting

12May has 31 daysWaiting

13June has 30 daysWaiting

14July and August both have 31 daysWaiting

15September has 30 daysWaiting

16October has 31 daysWaiting

17November has 30 daysWaiting

18December has 31 daysWaiting

19A leap year does not change AprilWaiting

20Every month of a leap yearWaiting

21Every month of a century yearWaiting

22Month 0 is invalidWaiting

23Month 13 is invalidWaiting

24A negative month is invalidWaiting

25A month far above 12 is invalidWaiting

26The extreme int values are invalid monthsWaiting