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

[Stephen23]

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!

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

[Karina Medina Barzola]

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

Answer 2

[Martín Avalos Postigo]

function valid = valid_date(year,month,day)
if sum(rem([year,month,day],1))==0 && sum([year,month,day]>0)==3
    if ismember(month,[1,3,5,7,8,10,12]) && day<32
        valid=true;
    elseif ismember(month,[4,6,9,11]) && day<31
        valid=true;
    elseif month==2 && ismember(sum(rem(year,[4,100,400])==0),[1,3]) && day<30
        valid=true;
    elseif month==2 && ismember(sum(rem(year,[4,100,400])==0),[0,2]) && day<29
        valid=true;
    else
        valid=false;
    end
else
    valid=false;
end

[Jaime Joaquin Moulic]

Thank you!!

Answer 3

[Jatan Shah]

function valid = valid_date (year, month, day)

if nargin<3

valid = false;

elseif ~isscalar(year) || year<1 || year~=fix(year)

valid = false;

elseif ~isscalar(month) || month<1 || month~=fix(month) || month>12

valid = false;

elseif ~isscalar(day) || 1>day || day~=fix(day) || day>31

valid = false;

elseif (month==4 || month==6 || month==9 || month==11) && day>30

valid = false;

elseif month==2 && day>29

valid = false;

elseif month==2 && day>28 && (year/4) ~= fix(year/4)

valid = false;

elseif (year/100)==fix(year/100) && (year/400)~=fix(year/400)

valid = false;

else

valid = true;

end

Answer 4

[S HARIPRAKASH]

valid date or not

function valid=valid_date(year,month,day)
%check whether the given input is scalar positive integer or not
%1<=day<=31
%1<=month<=12
if((~isscalar(year))||(~isscalar(month))||(~isscalar(day))||(year<=0)||(month<=0)||(day<=0)||(month>12)||(day>31)||(~(year==fix(year)))||(~(month==fix(month)))||(~(day==fix(day))))
    valid=false;
    return
end
%february has 29 days in leap year and 28 days in non leap year
if (month==2)
    if((mod(year,4)==0 && mod(year,100)~=0)||(mod(year,400)==0))
        if day<30
            valid=true;
            return
        else
            valid=false;
            return
        end
    else
        if day<29
            valid=true;return
        else
            valid=false;return
        end
    end
%check whether the number of given days is within the limit of days that particular month has.
else
    month_days=[31,28,31,30,31,30,31,31,30,31,30,31];
    if day<=month_days(month)
        valid=true;
        return
    else
        valid=false;
        return
    end
end
end

Answer 5

[VIGNESH B S]

function [valid] = valid_date(year,month,day)
 Entered = 0;
 
 if isscalar(year) == 0
     valid = logical(0);
     Entered = 1;
 elseif isscalar(month) == 0
     valid = logical(0);
     Entered = 1;
 elseif isscalar(day) == 0
     valid = logical(0);
     Entered = 1;
 end
 
 
 
      if year <= 0
          valid = logical(0);
          Entered = 1;
      elseif month <= 0
          valid = logical(0);
          Entered = 1;
      elseif day <= 0
          valid = logical(0);
          Entered = 1;
      end
      
  
      
leap_year = 0;
if(mod(year,4) == 0)
    leap_year = 1;
    if mod(year,100) == 0
       if mod(year,400) == 0
           leap_year = 1;
       else
           leap_year = 0;
       end
    end
end


if [leap_year,month,day] == [0,2,29]
    valid = logical(0);
    Entered = 1;
end

if [leap_year,month,day] == [1,2,29]
    valid = logical(1);
end



     if month == 1
         if day >= 32
             valid = (0>1);
             Entered = 1;
         end
     elseif month == 10
         if day >= 32
             valid = (0>1);
             Entered = 1;
         end
      elseif month == 8
         if day >= 32
             valid = (0>1);
             Entered = 1;
         end
       elseif month == 7
         if day >= 32
             valid = (0>1);
             Entered = 1;
         end
        elseif month == 5
         if day >= 32
             valid = (0>1);
             Entered = 1;
         end
        elseif month == 3
         if day >= 32
             valid = (0>1);
             Entered = 1;
         end
         elseif month == 12
         if day >= 32
             valid = (0>1);
             Entered = 1;
         end
         
     elseif month == 4
         if day >=  31
             valid = logical(0);
             Entered = 1;
         end
     elseif month == 9
         if day >=  31
             valid = logical(0);
             Entered = 1;
         end
     elseif month == 6
         if day >=  31
             valid = logical(0);
             Entered = 1;
         end
     elseif month == 11
         if day >=  31
             valid = logical(0);
             Entered = 1;
         end
     end

     if month == 2
         if day >= 30
            Entered = 1;
         valid = logical(0); 
         end
     end
        
     if month >= 13
         Entered = 1;
         valid = logical(0);
     end
     
     
if Entered == 0
    valid = logical(1);
end
     
end

%A HELL LINES OF CODES!!!!!!! BUT IT WORKED OUT !!

Answer 6

[Karnajit Banik]

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

Answer 7

[Fazal Hussain]

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

Answer 8

[Erikc Anderson Cortez Benites]

function valid = valid_date(year, month, day)
if isscalar(year) && isscalar(month) && isscalar(day)
    if month < 1 ||  month > 12
        valid = false;
    else
        if month == 2 && isleapyear(year)
           valid = day <= 29 && day>0 ;  
        elseif sum(month == [1,3,5,7,8,10,12])
            valid = day <= 31 && day>0;  
        else
            valid = day <= 30 && day>0; 
        end
    end
else 
    valid = false;
end 


function re = isleapyear(year)
if mod(year,400) == 0
    re = 1;
elseif (mod(year,4) == 0) && (mod(year,100)) ~= 0 
    re = 1;
else
    re = 0;
end

Answer 9

[Ravleen Kaur]

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

Answer 10

[David Goh]

function valid = valid_date(year,month,day)

if isscalar(year) == 1 && isscalar(month) == 1 && isscalar(day) == 1 && year > 0 && month > 0 && day > 0
    if month <= 12
        if (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 == 2
            if (rem(year,4)==0 || rem(year,400)==0) && (rem(year,400)~=100 && rem(year,400)~=200 && rem(year,400)~=300)
                if day <= 29
                    valid = true;
                else 
                    valid = false;
                end
            else 
                if day <= 28
                    valid = true;
                else 
                    valid = false;
                end
            end
        else 
            if day <= 30
                valid = true;
            else 
                valid = false;
            end
        end
    else 
        valid = false;
    end
else 
    valid = false;
end