If else problem homework

Hi everyone, the howework question is :

Write a function called valid_date that takes three positive integer scalar inputs year, month, day. If these three represent a valid date, return a logical true, otherwise false. The name of the output argument is valid. If any of the input is not a positive integer scalar, return false as well. Note that every year that is exactly divisible by 4 is a leap year, except for years that are exactly divisible by 100. However, years that are exactly divisible by 400 are also leap years. For example, the year 1900 was not leap year, but the year 2000 was. Note that your solution must not contain any of the date related built-in MATLAB functions.

My code as an answer to this question was:

function a = valid_date(y,m,d)
if ~isscalar(y) || ~isscalar(m)|| ~isscalar(d)
    a = false;
else
    if m>=1 && m<=12
        if m==1||m==3||m==5||m==7||m==8||m==10||m==12
            if d>=1 && d<=31
                a = true;
            else
                a = false;
            end
        elseif m==4||m==6||m==9||m==11
            if d>=1 && d<=30
                a = true;
            else 
                a = false;
            end
        else
            if rem(y,4)==0 && rem(y,100)~=0
                if d>=1 && d<=29
                    a = true;
                else 
                    a = false;
                end
            elseif rem(y,400)==0
                if d>=1 && d<=29
                    a = true;
                else
                    a = false; 
                end
            else
                if d>=1 && d<=28
                    a = true;
                else
                    a = false;
                end
            end
        end
    else
        a = false;
    end
end

but I wonder that if there is a shorter answer (but sticking to the limitations of the question). If there is one, I'll be waiting for your answers.

Thank you !!

Answer 1

[Image Analyst]

Requirement say "The name of the output argument is valid." but you have

function a = valid_date(y,m,d)

instead of

function valid = valid_date(y,m,d)

Also, your function does not always return a value should there be some error thrown. That's why it's best to set a default immediately upon entering the function, not buried inside if blocks. A bonus of doing that is you can avoid lots of else blocks

function valid = valid_date(y,m,d)
valid = false;
if ~isscalar(y) || ~isscalar(m)|| ~isscalar(d)
	return;
end
% Make 2 digit years in the 2000's
if y < 1000
	y = y + 2000;
end
% Check by month.
if m >= 1 && m <= 12
	if m==1||m==3||m==5||m==7||m==8||m==10||m==12
		% January, March, May, July, August, October, December.
		if d>=1 && d<=31
			valid = true;
		end
	elseif m==4||m==6||m==9||m==11
		% April, June, September, November
		if d>=1 && d<=30
			valid = true;
		end
	else
		% February.  Check leap year rules.
		if rem(y,4)==0 && rem(y,100)~=0
			if d>=1 && d<=29
				valid = true;
			end
		elseif rem(y,400)==0
			if d>=1 && d<=29
				valid = true;
			end
		else
			if d>=1 && d<=28
				valid = true;
			end
		end
	end
end
end

[Berk Öztürk]

thank you for your answer, it helped a lot.