If else condition to determine if a year is a leap year

Hi there. Given a variable Y which stores a year in the 20th century (between 1901 and 2000), write MATLAB code to create a variable Days and assign it a value of 366 if the year is a leap year or a value of 365 otherwise.

[Jos (10584)]

Homework, not? What did you try yourself?

Answer 1

[Jos (10584)]

function Days = GetDays (Y)
if isLeapYear(Y)
   Days = 365 ;
else
   Days = 366 ;
end

Now your problem is to write second function IsLeapYear that returns true for leap years. (hint: see Nitin's answer)

[chafah zachary]

Thank you Jos. I got it

Answer 2

[Nitin]

These are the conditions for a leap year :

• The year is evenly divisible by 4;
• If the year can be evenly divided by 100, it is NOT a leap year, unless;
• The year is also evenly divisible by 400. Then it is a leap year.

I have done the first part, I'll leave the rest to you to implement

if mod(year,4)== 0 % use the modulo operator to check for remainder

days == 366

else

days == 365

end

http://en.wikipedia.org/wiki/Leap_year

[chafah zachary]

Thank you Nitin

Answer 3

[Ian]

ndays = datenum(Y+1,0,0) - datenum(Y,0,0);

isleap = ndays == 366;

Answer 4

[Shikhar Srivastava]

if(year/4==0 || year/400==0 && ~((year/100==0)))

[Stephen23]

"(year/4==0 || year/400==0 && ~((year/100==0)))"

The only year that satisifes the condition is year=0. I doubt that this is very useful.

We can check this approach easily by using array division rather than matrix division:

>> Y = [0;1;2;3;4;5;6;7;8;9];
>> (Y./4==0 | Y./400==0 & ~((Y./100==0))) % only Y=0 -> true
ans =
  1
  0
  0
  0
  0
  0
  0
  0
  0
  0
>> Y = 1900:2023;
>> any(Y./4==0 | Y./400==0 & ~((Y./100==0)))
ans = 0

Apparently there were no leap years in the previous century.

[Shikhar Srivastava]

i m considering years>1000

[Rik]

Complete code posted as answer in another thread:

%sir, i wrote this code,but it is passing nly random leap yeara,can u point out the mistake.%
function valid=valid_date(year,month,day)
if(year/4==0 || (year/400==0 && ~((year/100==0))))
    if(3<=month && month<13 || month==1  && 1<=day && day<32)
        valid=true;
    elseif(month==2 && 1<=day && day<30)
        valid=true;
    else
        valid=false;
    end

else
    if(3<=month && month<13 || month==1  && 1<=day && day<32)
        valid=true;
    elseif (month==2 && 1<=day && day<29)
        valid=true;
    else
        valid=false;
    end
end

[Rik]

You are using division. Consider the year 2004, which was a leap year. What happens for each of your checks?

year/4==0% year/4 is 501, so this returns false
year/400==0% year/400 is 5.01, so this returns false
~(year/100==0)% year/100 is 20.04, so this returns true

%so your if is this:
if false || (false && true)

If you describe it with words, what is the condition to check if a year is a leap year?