# 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

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Ajith Thomas on 29 Jun 2019
Commented: Rik on 21 Oct 2020 at 11:57
unction valid=valid_date(year,month,date)
if nargin==3
valid1=true;
else valid=false;
return
end
v1=[year]; v2=[month]; v3=[date];
if isscalar(v1)==true && isscalar(v2)==true && isscalar(v3)==true
valid2=true;
else valid=false;
return
end
if year>0 && 0<month && month<=12 && 0<date && date<=31
valid3=true;
else valid=false;
return
end
a=year/4; b=year/100; c=year/400;
if rem(year,4)==0 && rem(year,100)~=0
valid4=true;
else valid4=false;
end
if rem(year,100)==0 && rem(year,400)~=0
valid5=true;
else valid5=false;
end
if rem(year,400)==0
valid4=true;
else valid4=false;
end
if (month==1||3||5||7||8||10||12 && date<=31) || (month==2 && date<=29) || (month==4||6||9||11 && date<=30) && valid4==true && valid5==false
valid6=true;
else valid6=false;
end
if (month==1||3||5||7||8||10||12 && date<=31) || (month==2 && date<=28) || (month==4||6||9||11 && date<=30) && valid5==true && valid4==false
valid7=true;
else
valid7=false;
end
if valid1==true && valid2==true && valid3==true && valid6==true
valid=true;
elseif valid1==true &&valid2==true && valid3==true && valid7==true
valid=true;
else
valid=false;
return
end
why this code is not working for 2018/4/31 and 2003/2/29? and other random dates. but is works for non scalar and random leap years

Stephen Cobeldick on 29 Jun 2019
Julian Veran on 18 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
Walter Roberson on 18 May 2020
Julian,
before posting, please use the MATLAB editor to "smart indent". Then when you post, first click on the '>' button in the CODE toolbar section of the Answers editor, and then paste the code into the highlight box that appears: that will cause the code to be posted in formatted form.

SANTOSH KAMBLE on 3 May 2020
Edited: SANTOSH KAMBLE on 4 May 2020
function [valid]=valid_date(year,month,date)
y=year;m=month;d=date;
if ~isscalar(y)|| ~isscalar(m) || ~isscalar(d)
valid=false;
return
end
if y>=1 && m==1 && d>=1 && d<=31
valid=true;
elseif y>=1 && m==2 && d>=1 && d<=28 && mod(y,4)~=0
valid=true;
elseif y>=1 && m==2 && d>=1 && d<=29 && ((mod(y,4)==0 && mod(y,100)~=0 )|| mod(y,400)==0)
valid=true;
elseif y>=1 && m==3 && d>=1 && d<=31
valid=true;
elseif y>=1 && m==4 && d>=1 && d<=30
valid=true;
elseif y>=1 && m==5 && d>=1 && d<=31
valid=true;
elseif y>=1 && m==6 && d>=1 && d<=30
valid=true;
elseif y>=1 && m==7 && d>=1 && d<=31
valid=true;
elseif y>=1 && m==8 && d>=1 && d<=31
valid=true;
elseif y>=1 && m==9 && d>=1 && d<=30
valid=true;
elseif y>=1 && m==10 && d>=1 && d<=31
valid=true;
elseif y>=1 && m==11 && d>=1 && d<=30
valid=true;
elseif y>=1 && m==12 && d>=1 && d<=31
valid=true;
else
valid=false;
end
end

Shaked Baharav on 27 Sep 2020 at 8:12
Hello, Can you explain to me what you did in the code?
anil Reddy on 21 Oct 2020 at 11:42
if i take (0<month<=12) in place of ((12>=month) && (month>0)) why am i getting mistake
Rik on 21 Oct 2020 at 11:57
Because that is not how Matlab operations work. The explanation provided by mlint explains it:

per isakson on 29 Jul 2020
Edited: per isakson on 29 Jul 2020
Would this function pass?
function [ valid, dt ] = valid_date( y, m, d )
% The names of the input arguments, (year,month,day), are they
% mandatory? Are these names chosen to shadow functions in the
% finance toolbox?
try
% datetime is "smart". Doc says: "Each element of DateVector
% should be a positive or negative integer value [...]. If an
% element falls outside the conventional range, datetime adjusts
% both that date vector element and the previous element."
dt = datetime( y, m, d );
% If datetime didn't adjust any element the input is a
% valid date.
% valid = all( [ year(dt)==y, month(dt)==m, day(dt)==d ] );
vec = datevec( dt );
valid = all( [ vec(1)==y, vec(2)==m, vec(3)==d ] );
catch
% datetime throws an exception when not all input values are
% integers
dt = datetime.empty;
valid = false;
end
end

#### 1 Comment

Rik on 13 Aug 2020
I would hope so. As an instructor I would applaud lateral thinking like this. Just as I would accept code where someone did this:
for n=1%use a loop because it is a requirement
output=sum(data,2);
end

Iccu OUMOUACHA on 25 May 2020
function valid=valid_date(year, month, day)
if year<=0 || month<=0 || day<=0 || mod( year , 1 )~=0 || mod( month , 1 )~=0 || mod( day , 1 )~=0
valid=false;
return
end
if month<=12 && (ismember(month, [4 6 9 11]) && ismember(day, [1:30]))
valid=true;
elseif month<=12 && (ismember(month, [1 3 5 7 8 10 12]) && ismember(day, 1:31))
valid=true;
elseif month==2 && (mod(year,4)==0 && mod(year,100)~=0 || mod(year,400)==0 && mod(year,100)==0) && ismember(day, 1:29)
valid=true;
elseif month==2 && ismember(day, 1:28)
valid=true;
else
valid=false;
return
end
end
it works in Matlab, when I test a non-scalar inputs, it return false. But here it doesn't work!!!!! ((Assessment 2))
What is the problem?

Rik on 25 May 2020
It doesn't return false, it returns an error:
valid_date([2020 2020], 11, 5)
Iccu OUMOUACHA on 25 May 2020
the problem remained
Rik on 25 May 2020
Then you should change your code.
If you think this comment is unhelpful: show the code you used to ensure the output is false for non-scalar inputs. That is the only way someone will be able to help you.

Capulus_love on 11 Aug 2020
Edited: per isakson on 11 Aug 2020
function x = valid_date(year,month,day)
if nargin == 3
if isscalar(year) && isscalar(month) && isscalar(day)
if month > 0 && month <= 12 && day >= 0 && year > 0
if (month == 1 || 3 || 5 || 7 || 8 || 10 || 12 && day <= 31)...
|| (month == 2 && day <= 29) && (month == 4 || 6 || 9 || 11 && day <= 30)
c0 = mod(year,4)
c1 = mod(year,100)
c2 = mod(year,400)
if (c0 == 0 && c1 ~=0) || (c1 == 0 && c2 ~= 0) || c2 == 0
x = 'true'
else
x = 'false'
end
else
x = 'false'
end
else
x = 'false'
end
else
x = 'false'
end
else
x = 'false'
end
end
why this code not working? :(

#### 1 Comment

Rik on 11 Aug 2020
Let's try some cases that will likely point us to an issue:
valid_date(2020,2,29) %returns true
valid_date(2021,2,29) %returns false
valid_date(2021,2,28) %returns false
That last one is a problem. Can you follow the flow of your code where it should mark Feb 29 as valid only in leap years, and the rest of Feb as valid every year?
Also, your code returns the value as a char array, not a logical.