Write a function three positive integer scalar inputs year, month, day.

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. Note that every year that is exactly divisible by 4 is a leap year, except for years that are exactly divisible by 100. However, years that are exactly divisible by 400 are also leap years. For example, the year 1900 was not leap year, but the year 2000 was.

%Code to call your function
valid = valid_date(2018,4,1)
valid = valid_ date(2018,4,31)

I only got 1 of 6 which is random leap years.

Here is my code.

function valid = valid_date(year,month,day)
if ~isscalar(year) || year <1 || year ~= fix(year);
    valid = false;
end
if ~isscalar(month) || month <1 || month ~= fix(month) || month > 12;
    valid = false;
end
if ~isscalar(day) || day <1 || day ~= fix(day) || day > 31;
    valid = false;
end
if year/4 == 0 && year/100 == 0 && year/400 == 0;
    if month == [2,4,6,9,11];
        if month == 2 && day > 29;
            valid = false;
        elseif month ~= 2 && day > 30;
            valid = false;
        else
            valid = true;
        end
    else month ~= [2,4,6,9,11];
        if day > 31;
            valid = false;
        else
            valid = true;
        end
    end
elseif year/4 == 0 && year/100 ~= 0 && year/400 ~= 0;
    if month == [2,4,6,9,11];
        if month == 2 && day > 29;
            valid = false;
        elseif month ~= 2 && day > 30;
            valid = false;
        else
            valid = true;
        end
    else month ~= [2,4,6,9,11];
        if day > 31;
            valid = false;
        else
            valid = true;
        end
    end
elseif year/4 == 0 && year/100 == 0 && year/400 ~= 0;
    if month == [2,4,6,9,11];
        if month == 2 && day > 28;
            valid = false;
        elseif month ~= 2 && day > 30;
            valid = false;
        else
            valid = true;
        end
    else month ~= [2,4,6,9,11];
        if day > 31;
            valid = false;
        else
            valid = true;
        end
    end
else year/4 ~= 0 && year/100 ~= 0 && year/400 ~= 0;
    if month == [2,4,6,9,11];
        if month == 2 && day > 28;
            valid = false;
        elseif month ~= 2 && day > 30;
            valid = false;
        else
            valid = true;
        end
    else month ~= [2,4,6,9,11];
        if day > 31;
            valid = false;
        else
            valid = true;
        end
    end
end

[Ioannis Andreou]

What exactly is your question?

[Mohammad Sami]

There are a few issues with your code.

1. For the first three if statements checking the validity of the input, add a return statement after valid = false. This will prevent the rest of your code from executing.
2. when you are equating month with an array month == [2,4,6,9,11], this returns a logical array. You need a logical scalar. use function any or all to convert logical array to a scalar. e.g. any(month == [2,4,6,9,11])
3. your condition year/4 and others are not giving you the remainder, you need to use mod or rem function to get the remainder

[Taekyoung Lee]

@Mohammad Sami

Thank you for your support! I got 6 of 6!! Thank you so much ones agian.

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

[Abhishek Kumar]

%This is the working code
function [valid] = valid_date(y, m, d)
t = isscalar(y) && isscalar(m) && isscalar(d)
if t ~= 1
    valid = false;
else nargin == 3 && (y && m > 0) 
      
  p = rem(y,4);
  q = rem(y,100);
  r = rem(y,400);
  
  if (p == 0 && q ~= 0) || r == 0
      if (m == 1 || m == 3 || m == 5 || m == 7 || m == 8 || m == 10 || m == 12) && (d > 0 && d <= 31)
          valid = true;
      elseif (m == 4 || m == 6 || m == 9 || m == 11) && (d > 0 && d <= 30)
          valid = true;
      elseif m == 2 && (d > 0 && d <= 29)
          valid = true;
      else
          valid = false;
      end
  else
      if (m == 1 || m == 3 || m == 5 || m == 7 || m == 8 || m == 10 || m == 12) && (d > 0 && d <= 31)
          valid = true;
      elseif (m == 4 || m == 6 || m == 9 || m == 11) && (d > 0 && d <= 30)
          valid = true;
      elseif m == 2 && (d > 0 && d <= 28)
          valid = true;
      else
          valid = false;
      end
  end
  end

Answer 1

[Subhadeep Koley]

Refer the code below. Hope this helps!

function valid = validateDate(year, month, day)
    year1 = year/4;
    leap1 = year1 == round(year1); % Condition 1

    year2 = year/100;
    leap2 = year2 == round(year2); % Condition 2

    year3 = year/400;
    leap3 = year3 == round(year3); % Condition 3

    if leap1
        leapYear = 1;
    elseif leap2
        leapYear = 0;
    elseif leap3
        leapYear = 1;
    else
        leapYear = 0;
    end
    if isscalar(year) && year >= 1 && isscalar(month) && month >= 1 && month <= 12 && isscalar(day) && day >= 1 && day <= 31
        if leapYear
            if month == 2
                valid = day <= 29;
            elseif month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12
                valid = day <= 31;
            else
                valid = day <= 30;
            end
        else
            if month == 2
                valid = day <= 28;
            elseif month == 1 || month ==3 || month ==5 || month ==7 || month == 8 || month == 10 || month == 12
                valid = day <= 31;
            else
                valid = day <= 30;
            end
        end
    else
        valid = false;
    end
end

Answer 2

[Ahmed BENTALEB]

My solution, it passed all tests and for sure it could be optimized more. hope it helps

function valid = valid_date(year, month, day)
valid = false;
if checkinput(year) && checkinput(month) && checkinput(day)
    if isleap(year)
        valid = (month31(month) && day<=31) || (month30(month) && day<=30) || (month==2 && day<=29);
    else
        valid = (month31(month) && day<=31) || (month30(month) && day<=30) || (month==2 && day<=28);
    end
end


% check correct input
function check = checkinput(in)
 check = isscalar(in) && in >=1 && in == fix(in);

% check for leap year to handel month 2
function leap = isleap(y)
 leap = (mod(y,4)==0 && ~mod(y,100)==0) || mod(y,400)==0;

 % check for lmonths where days are 31 or less
function is31 = month31(month)
 is31 = (month==1 || month==3 || month==5 || month==7 || month==8 || month==10 || month==12);

 % check for lmonths where days are 30 or less
function is30 = month30(month)
 is30 = (month==4 || month==6 || month==9 || month==11);

Edit: another solution combined with the solution from cours

function valid = valid_date(y, m, d)
valid = false;
% check all input conditions one time
if checkinput(y) && (checkinput(m) && m<=12) && (checkinput(d) && d<=31)
    % days of month in a year
    daysInMonth = [31 28 31 30 31 30 31 31 30 31 30 31];
    if isleap(y)
        daysInMonth(2) = 29; % change month 2 days to 29
    end
    valid = d<=daysInMonth(m);
end

% check correct input
function check = checkinput(in)
 check = isscalar(in) && in >=1 && in == fix(in);
 
% check for leap year to handel month 2
function leap = isleap(y)
 leap = (mod(y,4)==0 && ~mod(y,100)==0) || mod(y,400)==0;

Answer 3

[Paul]

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

[DGM]

Same comment as before:

https://www.mathworks.com/matlabcentral/answers/469201-write-a-function-called-valid_date-that-takes-three-positive-integer-scalar-inputs-year-month-day#comment_2858907

https://www.mathworks.com/matlabcentral/answers/469201-write-a-function-called-valid_date-that-takes-three-positive-integer-scalar-inputs-year-month-day#answer_1292512