Stuck on checking for leap year and a valid date

Question

I wrote this code to check for date validation, but I am stuck on how to check for leap year.

date = '01/02/1990';
display('hello')
a=strsplit(date,'/');
day = a(1);
display(day);

%b=strsplit('/',date,'/');
month = a(2);
display(month);

%c=strsplit('/','/',date);
year = a(3);
display(year);

if (month==1||month==3||month==5||month==7||month==8||month==10||month==12)
    if (day>=1&&day<=31)

        display(' Its a valid date')
    else
        display(' Its NOT a valid date')
    end
end 

How do I incorporate leap year calculation?

Answer 1

Thanks to @gregswiss for pointing out my error in leap year calculation. This directly incorporates the check into the code, thus you do not have to include an a priori list of leap years:

if (mod(year,4) == 0 && mod(year,100) ~= 0) || mod(year,400) == 0
     disp('Leap year'); 
else
     disp('Non-leap year'); 
end

Just include this in your if statement the same way you check your months. Then if your year has a corresponding entry in LeapYear it is a leap year:

if sum(year==LeapYear)
    disp('This is a leap year')
end

The reason for the sum is that year==LeapYear will be a logical array containing 30 values, of which 29 zero and 1 one if your year is indeed a leap year, or it will contain 30 zeros. I recently found out about a more obscure function: eomday which tells you the last day of the month, so a simple eomday(year,month)==29 is sufficient to tell you whether it is a leap year. (There's [leapyear][2] as well, but that's in the aerospace toolbox)

    date = input('Please enter a date in the DD/MM/YYYY format ','s')
    display('hello')
    tmp=strsplit(date,'/');
    a(1) = str2num(tmp{1}); % Create an array out of your string
    a(2) = str2num(tmp{2});
    a(3) = str2num(tmp{3});
    day = a(1);
    display(day);

     month = a(2);
     display(month);

    year = a(3);
    display(year);
    if eomday(year,month)==29
         disp('Leap year'); 
    else
         disp('Non-leap year'); 
    end
    %if (mod(year,4) == 0 & mod(year,100) ~= 0) | mod(year,400) == 0
    %     disp('Leap year'); 
    %else
    %     disp('Non-leap year'); 
    %end
      if (month==1||month==3||month==5||month==7||month==8||month==10||month==12)
       if (day>=1&&day<=31)

         display(' It is a valid date')
   else
         display(' It is NOT a valid date')
           end
       end