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.

Hi Folks,

I have tried and ended up in errors. For example(valid_date(2018, 4, 1) failed,The last day of every month

Variable valid has an incorrect value. valid_date(2000, 1, 31) failed..., Random leap years

Variable valid has an incorrect value. valid_date(1624, 2, 29) failed..., Random dates

Variable valid has an incorrect value. valid_date(1433, 6, 28) failed...)

Kindly point out the errors I have made!

function valid = valid_date(year,month,day)
if (nargin==3)
    if (fix(valid_date)&&isscalar(valid_date))
        if((rem(year,4)==0||rem(year,400)==0) && rem(year,100)~=0)
            if((month==1||3||5||7||9||11) && 0<day<32)
            valid=true;
            elseif(month==2 && 0<day<30)
            valid=true;
            elseif((month==4||6||8||10||12) && 0<day<31)
            valid=true;
            else
            valid=false;    
            end
        else
            if((month==1||3||5||7||9||11) && 0<day<32)
            valid=true;
            elseif((month==4||6||8||10||12) && 0<day<31)
            valid=true;
            elseif(month==2 && 0<day<29)
            valid=true;
            else
            valid=false;
            end
        end
        else
        valid=false;
        end
    else
        valid=false;
    end

[Stephen Cobeldick]

Note that this syntax

month==1||3||5||7||9||11

is equivalent to:

(((((month==1)||3)||5)||7)||9)||11

which, because 11 is non-zero, will always be true. You should start thinking about using vectors, which would make that comparison easy (hint: use any)

[Guillaume]

As Stephen points out, inventing your own syntax for the if tests is not going to work very well. Note that to check if a number is a member of the set {a,b,c}, you'd use ismember(x, [a, b, c]), not some invented x==a||b||c syntax.

In this case, it didn't even matter that the comparison didn't make sense because of:

if fix(valid_date)&&isscalar(valid_date)  %removed unnecessary parentheses
    %...
end

which recurse into valid_date, this time with no argument. Since valid_date with 0 inputs always return false (thankfully, breaking the recursion), and since fix(false) is always false, the above if is always false.

As coded, the function can be simply reduced to

function valid = valid_date(~, ~, ~)
    valid = false;
end

[Rakeshwar Elango]

Thank you Stephen and Guillaume as the newly invented statement of me didn't through any error so I was wandering wheather where it went wrong. Thank you for your suggesion!

[Rakeshwar Elango]

I have debugged the code and now the Scalar test for this code is failing although I have given a provition in the 3rd line of the code to check wheather the given inputs are scalar or not.

please help!

function valid = valid_date(year,month,day)
if nargin==3
    if fix(month) && isscalar(month) && fix(day) && isscalar(day) && fix(year) && isscalar(year) && isscalar(valid_date) && year>0 && month>0 && day>0
        if mod(year,4)==0&&mod(year,100)~=0 || mod(year,400)==0&&mod(year,100)==0
            if ismember(month,[1,3,5,7,8,10,12]) && ismember(day,[1:31])
            valid=true;
            elseif month==2 && ismember(day,[1:29])
            valid=true;
            elseif ismember(month,[4,6,9,11]) && ismember(day,[1:30])
            valid=true;
            else
            valid=false;    
            end
        else
            if ismember(month,[1,3,5,7,8,10,12]) && ismember(day,[1:31])
            valid=true;
            elseif ismember(month,[4,6,9,11]) && ismember(day,[1:30])
            valid=true;
            elseif month==2 && ismember(day,[1:28])
            valid=true;
            else
            valid=false;
            end
        end
    else
    valid=false;
    end
else
valid=false;
end


 Assessment result: correctVarious inputs
 Assessment result: incorrectNon-scalar
Return false if an input is not scalar...
 Assessment result: correctThe last day of every month
 Assessment result: correctRandom leap years
 Assessment result: correctRandom non-leap years
 Assessment result: correctRandom dates

[pratish dewangan]

No need of fix function here , they should be remove

[pradeep kumar]

that code is working for scalar input

[Amina Sadia]

function valid = valid_date(year,month,date)
a = rem(year,400);
b = rem(year,4);
c = rem(year,100);
%check if either year, month, day is not a scalar
if ~isscalar(year) || ~isscalar(month) || ~isscalar(date)
valid =false
return
end
%checking integer
e = rem(year,1)+rem(month,1)+rem(date,1)

if year > 0 && month > 0 && month <=12 && date > 0 && date <= 31 && e==0
    if (month == 4 || month == 6 || month == 9 || month == 11) && date <=30
        valid = true;
    elseif (month == 1 || month == 3 ||month == 5 || month == 7 || month == 8 || month == 10 || month == 12) && date <=31
        valid = true;
    elseif month == 2 && a == 0 && date <=29
        valid = true;
    elseif month == 2 && b == 0 && c ~= 0 && date <=29
        valid = true;
    elseif month == 2 && date <=28
        valid = true;
    else
        valid = false;
    end
else
    valid = false;
end

Answer 1

[James Tursa]

Looks like you are taking the same class as Rahul. Rather than repeat my answer here, I will simply direct you to the link:

https://www.mathworks.com/matlabcentral/answers/466971-if-else-problem-for-year

[Gloria Paul]

Been stuck on this assignment for awhile now. Very close to giving up

Answer 2

[Thyagharajan K K]

valid = valid_date(2019, 12, 1)

function valid = valid_date(year,month,day)

%check if either year, month, day is not a scalar

if ~isscalar(year) || ~isscalar(month) || ~isscalar(day)

valid =false

return

end

%check if either year, month, day is 0 or negative. check if month is >12

if year<=0 || month>12 || month <=0 ||day<=0

valid =false

return

end

A = [1 3 5 7 8 10 12]; %months with 31 days

B = [4 6 9 11]; %months with 30days

month_31d = sum(ismember(A,month));

%ismember() returns a logical array where element found will be marked as 1 & other positions will be 0

%so only one element in this logical array will be 1 and other elements will be 0 if month falls in this

%month_31d category. Hence sum will be 1 i.e month_31d will be true.

month_30d = sum(ismember(B,month)); %same as above to check whether month falls in the category month_30d

%check for leap year

if rem(year,400)==0

leap_year = true;

elseif rem(year,4)==0 && rem(year,100) ~=0

leap_year =true;

else

leap_year = false;

end

%Check the days for the conditions 28,29,30,31

if month_31d && day>31

valid = false;

elseif month_30d && day>30

valid = false;

elseif (leap_year && month==2 && day>29)||(~leap_year&&month==2&&day>28)

valid = false;

else

valid =true;

end

end

[ManiSandeep Reddy]

function valid=valid_date(year,month,day)
if ~isscalar(year)||~isscalar(month)||~isscalar(day)
    valid=false;   
elseif year<0 || month<0 || day<0 || month>12 || day>31|| month==0 || day==0  || year ~= fix(year)||month ~= fix(month)||day ~= fix(day)
    valid=false;    
        
else
    if month==2
        if ((rem(year,4)==0 && rem(year,100)~=0)||rem(year,400)==0)
            if day>29
                valid=false;
            else
                valid=true;
            end
        else 
            if day>28
                valid=false;
            else
                valid=true;
            end
        end
    else
        if (month==4||month==6||month==9||month==11) && day==31
            valid=false;
        else
            valid=true;
        end
    end
end
end

Answer 3

[Amina Sadia]

function valid = valid_date(year,month,date)
a = rem(year,400);
b = rem(year,4);
c = rem(year,100);
%check if either year, month, day is not a scalar
if ~isscalar(year) || ~isscalar(month) || ~isscalar(date)
valid =false
return
end
e = rem(year,1)+rem(month,1)+rem(date,1)

if year > 0 && month > 0 && month <=12 && date > 0 && date <= 31 && e==0
    if (month == 4 || month == 6 || month == 9 || month == 11) && date <=30
        valid = true;
    elseif (month == 1 || month == 3 ||month == 5 || month == 7 || month == 8 || month == 10 || month == 12) && date <=31
        valid = true;
    elseif month == 2 && a == 0 && date <=29
        valid = true;
    elseif month == 2 && b == 0 && c ~= 0 && date <=29
        valid = true;
    elseif month == 2 && date <=28
        valid = true;
    else
        valid = false;
    end
else
    valid = false;
end