How to write a function to determine if a date entered is valid

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Elliot Ogbechina on 28 Dec 2019
Commented: Walter Roberson on 17 Jul 2020
I am to 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 inputs is not a positive integer scalar, return false as well. Here is the code i have tried but keeps returning true for all dates, I have editted it a lot and now i just need a fresh eye to point out what i am doing wrong:
NB: I am not to use any built in MatLab function.
function valid = valid_date (year, month, date)
if (nargin==3)
valid=true;
elseif (isinteger(year)) && year>0 && (isscalar(year))
valid=true;
elseif (isinteger(month))&& month>0 && month <=12 && (isscalar(month))
valid=true;
elseif (isinteger(date)) && date > 0 && (isscalar(date))
valid=true;
elseif (month==1||month==3||month==5||month==7||month==8||month==10||month==12)&& date<=31
valid=true;
elseif date <=30
valid=true;
elseif (isinteger(year/4)) && month == 2 && (~(isinteger(year/100))||(isinteger(year/400))) && date <= 29
valid=true;
else
valid = false;
end
Stephen23 on 31 Dec 2019
Edited: Stephen23 on 31 Dec 2019
"so what can i use in place of isinteger"
Take a look at this answer you were given six hours ago:
Does it use isinteger? (hint: no)
What does it use? (hint: mod)

aniket GIRI on 27 May 2020
function isvalid = valid_date(y, m, d)
% Check if the inputs are valid
% Check that they are scalars
if ~(isscalar(y) && isscalar(m) && isscalar(d))
isvalid = false;
% Check that inputs are positive
elseif ~all([y, m, d] > 0)
isvalid = false;
% Check that inputs are integers (not the data type)
elseif any(rem([y, m, d], 1))
isvalid = false;
% Check that m and d are below the max possible
elseif (m > 12) || (d > 31)
isvalid = false;
% The inputs could be a valid date, let's see if they actually are
else
% Vector of the number of days for each month
daysInMonth = [31 28 31 30 31 30 31 31 30 31 30 31];
% If leap year, change days in Feb
if isequal(rem(y, 4), 0) && (~isequal(rem(y, 100), 0) || isequal(rem(y, 400), 0))
daysInMonth(2) = 29;
end
maxDay = daysInMonth(m);
if d > maxDay
isvalid = false;
else
isvalid = true;
end
end
end

MUHAMMAD USMAN BIN AHMED on 1 Jun 2020
function valid = valid_date(year,month,day)
if nargin ~=3
valid=false;
elseif ((~isscalar(year))||(mod(year,1)~=0)||year<=0)
valid=false;
elseif ((~isscalar(month))||(mod(month,1)~=0)||month<=0||month>12)
valid=false;
elseif ((~isscalar(day))||(mod(day,1)~=0)||day<=0)
valid=false;
elseif (any(month==[1,3,5,7,8,10,12]) && day>31)
valid=false;
elseif (any(month==[4,6,9,11]) && day>30)
valid=false;
else
valid=true;
if (rem(year,4)==0 && month==2 && day<=29)
valid=true;
if (rem(year,100)==0)
valid=false;
if rem(year,400)==0
valid=true;
return
end
end
elseif month==2 && day>28
valid=false;
end
end
end
MUHAMMAD USMAN BIN AHMED on 1 Jun 2020
is this the correct one?

Jalaj Gambhir on 31 Dec 2019
Hi,
You can try the following function and see if it works for you:
function valid = valid_date(year, month, date)
if(nargin ~= 3)
valid = false;
elseif (~(mod(year,1)==0) || (year<0) || ~isscalar(year))
valid = false;
elseif (~(mod(month,1)==0) || (month<=0) || (month>12) || ~isscalar(month))
valid = false;
elseif (~(mod(date,1)==0) || (date<=0) || ~isscalar(date))
valid = false;
elseif( (month==1||month==3||month==5||month==7||month==8||month==10||month==12)&& date>31 )
valid = false;
elseif ((month==4||month==6||month==9||month==11) && date>30)
valid = false;
elseif(~leapyear(year) && month==2 && date>28)
valid=false;
elseif(leapyear(year) && month==2 && date>29)
valid=false;
else
valid = true;
end
Walter Roberson on 1 Jun 2020
Anil Muradiya which code are you finding is failing, and what inputs are you finding that it is failing on?

Sravani Kurma on 17 Jul 2020
Edited: Sravani Kurma on 17 Jul 2020
function valid=valid_date(year,month,date)
if nargin == 3;
if ~isscalar(year) || year<1|| year~=fix(year)||~isscalar(month) || month<1|| month~=fix(month)||~isscalar(date) || date<1|| date~=fix(date);
valid=false;
else
if ((year/100)~=fix(year/100)&&(year/4)==fix(year/4))||((year/400)==fix(year/400));
%leap yr
valid=mmm(month,date);
else
%non leap year
valid=sss(month,date);
end
end
end
function valid=mmm(month,date)
m30=[4,6,9,11];
m31=[1,3,5,7,8,10,12];
m29=2;
m28=2;
if max((month==m31)')==1
valid=(date>=1)&&date<=31;
elseif max(( month==m30)')==1
valid=(date>=1)&&date<=30;
elseif max((month==m29)')==1
valid=(date>=1)&&date<=29;
else
valid=false;
end
function valid=sss(month,date)
m30=[4,6,9,11];
m31=[1,3,5,7,8,10,12];
m29=2;
m28=2;
if max((month==m31)')==1
valid=(date>=1)&&date<=31;
elseif max(( month==m30)')==1
valid=(date>=1)&&date<=30;
elseif max((month==m28)')==1
valid=(date>=1)&&date<=28;
else
valid=false;
end
Walter Roberson on 17 Jul 2020
What will your code return if nargin is not 3?
if max((month==m31)')==1
Hint: any()

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