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Date Validation Logic and Error message

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Jack Crespo
Jack Crespo il 31 Mar 2019
Commentato: akhil soni il 5 Set 2020
I need help with writing a date validater in matlab without using built in time and date functions. It must check if a year is a leap year, and if so if february has no more than 29 days, and the other months satisfy their specific day maximums. If it isnt a leap year, then it checks if february has no more than 28 days, and the other months satisfy their specific day maximums. I have questions regarding checking if a year is a leap year and a new error message i have been getting.
1) Is my logic for checking for leap years correct? I used variables year1, year2, and year3 as assignments for the values of the year intputed divided by 4, 100, and 400, respectively. I then check if these values are evenly divided with the isfloat function. What would the correct logic look like?
2) I have been getting the error message "Output argument "valid" (and maybe others) not assigned during call to "valid_date"." What sources in my code could spark this error? I suspect i am overwriting the variable somehwere in my logic. I have done research to determine what this means and possible problems in the code and how to fix them, but I cannot for my life figure out what is causing the problem in my code.
I appreciate any comments. Please help because if have listened to every AC/DC album twice over while working on this code and i shouldnt have gray hair at 16 years old. I apoligize in advance for the quite messy code.
Thanks
function valid = valid_date(year, month, day)
year1 = year/4;
year2 = year/100;
year3 = year/400;
if isscalar(year) && year>=1 && isscalar(month) && month>=1 && month<=12 && isscalar(day) && day>=1 &&day<=31
if (~isfloat(year1) && ~isfloat(year2) && ~isfloat(year3)) || (~isfloat(year1) && isfloat(year2))
if month == 2
if day<=29
valid = true;
else
valid = false;
end
elseif month == 1 || month==3 || month==5 || month==7 || month==8 || month==10 || month==12
if day<=31
valid = true;
else
valid=false;
end
elseif month == 4 || month==6 || month==9 || month==11
if day <=30
valid=true;
else
valid=false;
end
else
valid=false;
end
else
if month <= 12
if month == 2 && day <=28
valid=true;
elseif month==1 || month==3 || month==5 || month==7 || month==8 || month==10 || month==12
if day > 31
valid = false;
else
valid=true;
end
else
if month == 4 || month==6 || month==9 || month==11
if day >30
valid=false;
else
valid=true;
end
end
end
else
valid=false;
end
end
else
valid = false;
end
end
  5 Commenti
Walter Roberson
Walter Roberson il 14 Feb 2020
You should not really be processing year to determine leap-year status until you have validated that year is a scalar positive integer.
akhil soni
akhil soni il 5 Set 2020
function valid = valid_date(year,month,day)
if (isscalar(year)==1 && isscalar(month)==1 && isscalar(day)==1)
if (month>12 || date>31)
valid=false;
else
if ((month==1||month==3||month==5||month==7||month==9||month==11) && (day>0 && day<32))
valid=true;
elseif ((month==4||month==6||month==8||month==10||month==12) && (day>0 && day<31))
valid=true;
elseif (month==2 && (year/400==fix(year/400)) && (day>0 && day<30))
valid=true;
elseif (month==2 && ((year/100==fix(year/100))&&(year/400~=fix(year/400))) && (day>0 && day<29))
valid=true;
elseif (month==2 && (year/100~=fix(year/100)) && (year/400~=fix(year/400)) && (year/400==fix(year/400)) && (day>0 && day<30))
valid=true;
else valid=false;
end
end
else valid=false;
end
end
% I have done this but error is shown in line 3 stating:- Operands to the || and && operators must be convertible to logical scalar values.
%what does this means?

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Risposte (4)

Neelkant Newra
Neelkant Newra il 14 Feb 2020
function valid = valid_date(year, month, day)
th31=[1,3,5,7,8,10,12];
th30=[4,6,9,11];
if isscalar(year) && year>=1 && isscalar(month) && month>=1 && month<=12 && isscalar(day) && day>=1 &&day<=31
if month == 2
if year/4 == fix(year/4)
if year/100 == fix(year/100) && year/400 == fix(year/400)
if day<=29
valid=true;
else
valid=false;
end
elseif year/100 == fix(year/100) && year/400 ~=fix(year/400)
if day <=28
valid = true;
else
valid = false;
end
else
if day <=29
valid = true;
else
valid =false;
end
end
else
if day<=28
valid= true;
else
valid=false;
end
end
elseif ismember(month,th31)
if day<=31
valid= true;
else
valid = false;
end
elseif ismember(month,th30)
if day<=30
valid = true;
else
valid = false;
end
end
else
valid= false;
end
  1 Commento
Walter Roberson
Walter Roberson il 14 Feb 2020
No point in figuring out whether you are dealing with a leap year unless you have been asked to validate 29th day of 2nd month.

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Rohan Singla
Rohan Singla il 23 Apr 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

Arafat Roney
Arafat Roney il 11 Mag 2020
function valid=valid_date(year,month,day)
if((isscalar(year))&&(isscalar(month))&&(isscalar(day)))
if((year==abs(fix(year)))&&(isscalar(year)))
y=true;
else y=false;
end
if((month<=12)&&(month==abs(fix(month)))&&(month>0)&&(isscalar(month)))
m=true;
else m=false;
end
if((rem(year,4)==0)&&(rem(year,100)~=0)&&(rem(year,400)~=0)||(rem(year,100)==0)&&...
(rem(year,400)==0))
feb=29;
else
feb=28;
end
if(((month==4)||(month==6)||(month==9)||(month==11))&&(day<=30)&&(day>0)&&(day==abs(fix(day)))&&(isscalar(day)))
d=true;
elseif((((month==1)||(month==3)||(month==5)||(month==7))||(month==8)||...
(month==10)||(month==12))&&(day<=31)&&(day>0)&&(day==abs(fix(day)))&&(isscalar(day)))
d=true;
elseif((feb==28)&&(month==2)&&(day<=28)&&(day>0)&&(day==abs(fix(day)))&&(isscalar(day)))
d=true;
elseif((feb==29)&&(month==2)&&(day<=29)&&(day>0)&&(day==abs(fix(day)))&&(isscalar(day)))
d=true;
else d=false;
end
if((y==true)&&(m==true)&&(d==true))
valid=true;
else
valid=false;
end
else
valid=false;
end
end
  1 Commento
Walter Roberson
Walter Roberson il 12 Mag 2020
If the year is non-scalar, then (year==abs(fix(year)) will be non-scalar, and you will have non-scalar && scalar which is an error. You need to test for scalar first.

Accedi per commentare.


Tahsin Oishee
Tahsin Oishee il 13 Mag 2020
function valid = valid_date(y,m,d)
if ~isscalar(y) && ~isscalar(m) && ~isscalar(d)
valid=false;
end
if y>0 && m>0 && m<12 && d>0 && d<31
valid=true;
else valid=false;
end
if m==1 && d==31
valid=true;
elseif m==3 && d==31
valid=true;
elseif m==4 && d>30
valid=false;
elseif m==5 && d==31
valid=true;
elseif m==6 && d>30
valid=false;
elseif m==7 && d==31
valid=true;
elseif m==8 && d==31
valid=true;
elseif m==9 && d>30
valid=false;
elseif m==10 && d==31
valid=true;
elseif m==11 && d>30
valid=false;
elseif m==12 && d==31
valid=true;
end
if m==2 && d==30 || d==31
valid=false;
end
if m==2 && rem(y,4)==0 && rem(y,100)~=0 && rem(y,400)~=0 && d==29
valid=true;
elseif m==2 && rem(y,100)==0 && rem(y,400)==0 && d==29
valid=true;
else valid=false;
end
end
  1 Commento
Walter Roberson
Walter Roberson il 13 Mag 2020
Modificato: Walter Roberson il 13 Mag 2020
Suppose y is not scalar but m and d are scalar. ~isscalar(y) would be true, but ~isscalar(m) would be false, and true && false is false, so you would not set valid=false.
Now suppose that y, m, and d are all not scalar, then ~isscalar(y) && ~isscalar(m) && ~isscalar(d) is true, so you set valid=false. But then regardless you go on to test y>0 && m>0 and so on, which would be testing the non-scalar values and using && between the tests, which is going to be an error.
Now suppose y is -7 and m = 1 and d = 31, then y > 0 is false so y>0 && m>0 && m<12 && d>0 && d<31 is false so you set valid=false. But then you go into the if/elseif tree and m==1 && d==31 is true so you set valid=true even though the year is invalid.
Generally speaking, you should set up valid=true at the beginning, and then do tests rejecting cases by setting valid=false, and as soon as you get one valid=false then you can skip the rest of the tests.

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