Validation of a date in given format

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. Note that your solution must not contain any of the date related built-in MATLAB functions.

[per isakson]

Homework? See How do I get help on homework questions on MATLAB Answers?

Answer 1

[Vinay Ram Gazula]

function valid = valid_date(y,m,d)
if nargin == 3
    if ~isscalar(y) || y < 1 || y ~= fix(y)
        valid = false;
        return
    elseif ~isscalar(m) || m < 1 || m ~= fix(m)
        valid = false;
        return
    elseif ~isscalar(d) || d < 1 || d ~= fix(d)
        valid = false;
        return
    end
end
a=y/4;b=y/400;c=y/100;
M1 = [1 3 5 7 8 10 12];
M2 = [4,6,9,11];
F1 = (1:29);
F2 = (1:28);
D1 = (1:31);
D2=(1:30);
if a ~= fix(a) || (b ~= fix(b) && c == fix(c))
    if ismember(m,M1) && ismember(d,D1)
            valid = true;
    elseif ismember(m,M2) && ismember(d,D2)
            valid = true;
    elseif m==2 && ismember(d,F2)
            valid = true;
    else
        valid = false;
    end
elseif a == fix(a) || b == fix(b)
    if ismember(m,M1) && ismember(d,D1)
            valid = true;
    elseif ismember(m,M2) && ismember(d,D2)
            valid = true;
    elseif m==2 && ismember(d,F1)
            valid = true;
    else
        valid = false;
    end   

end
end  

Answer 2

[Shubhadeep Sadhukhan]

function valid = valid_date(y,m,d)
if nargin == 3
    if ~isscalar(y) || y < 1 || y ~= fix(y)
        valid = false;
        return
    elseif ~isscalar(m) || m < 1 || m ~= fix(m)
        valid = false;
        return
    elseif ~isscalar(d) || d < 1 || d ~= fix(d)
        valid = false;
        return
    end
end
a=y/4;b=y/400;c=y/100;
M1 = [1 3 5 7 8 10 12];
M2 = [4,6,9,11];
F1 = (1:29);
F2 = (1:28);
D1 = (1:31);
D2=(1:30);
if a ~= fix(a) || (b ~= fix(b) && c == fix(c))
    if ismember(m,M1) && ismember(d,D1)
            valid = true;
    elseif ismember(m,M2) && ismember(d,D2)
            valid = true;
    elseif m==2 && ismember(d,F2)
            valid = true;
    else
        valid = false;
    end
elseif a == fix(a) || b == fix(b)
    if ismember(m,M1) && ismember(d,D1)
            valid = true;
    elseif ismember(m,M2) && ismember(d,D2)
            valid = true;
    elseif m==2 && ismember(d,F1)
            valid = true;
    else
        valid = false;
    end   
end
end 

[Walter Roberson]

What if nargin is not 3 ?

Is it possible for both your if a and elseif a to fail? If so what should happen? If not then you do not need all of the tests that you have.

[OUSSAMA El GABBARI]

I guess he forgot to put return after every valid = false and valid = true line.. right ??

Answer 3

[Cyrus David Pastelero]

%this is my stupid answer
function valid = valid_date(year, month, day)
    if  isscalar(year) && isscalar(month) && isscalar(day) && month <= 12 && day <= 31 && year > 40 && day > 0
        if(mod(year,400) == 0 || (mod(year,4) == 0 && mod(year,100) ~= 0))
            if(mod(month,2) ~= 0 && day <= 31 && month <= 7)
                valid = true;
            elseif(mod(month,2) == 0 && month ~= 2 && day <=30 && month <=7)
                valid = true;
            elseif(mod(month,2) == 0 && month ~= 2 && day <=31 && month >=8)
                valid = true;
            elseif(mod(month,2) ~= 0 && month ~= 2 && day <= 30 && month >=8)
                valid = true;
            elseif(month == 2 && day <= 29)
                valid = true;
            else
                valid = false;
            end
        else
            if(mod(month,2) ~= 0 && day <= 31 && month <= 7)
                valid = true;
            elseif(mod(month,2) == 0 && month ~= 2 && day <=30 && month <=7)
                valid = true;
            elseif(mod(month,2) == 0 && month ~= 2 && day <=31 && month >=8)
                valid = true;
            elseif(mod(month,2) ~= 0 && month ~= 2 && day <= 30 && month >=8)
                valid = true;
            elseif(month == 2 && day <= 28)
                valid = true;
            else
                valid = false;
            end
        end
    else
        valid = false;
    end
end

[Walter Roberson]

This is not MATLAB code. MATLAB does not permit // comments.

[Cyrus David Pastelero]

Yes, my bad. I'm a newbie in MatLab. I'm used in c++ syntax.

Answer 4

[ARNAB KARAK]

% but this is not wirking on non scalar variable
function valid = valid_date(year,month,day)
if (month==1||month==3||month==5||month==7||month==8||month==10||month==12)
    max_days=31;
elseif (month==4||month==6||month==9||month==11) 
    max_days=30;
elseif  mod(year, 4) == 0 && mod(year, 100) ~= 0|| mod(year, 400) == 0
    max_days=29
else max_days=28  
end
if (month<1) || (month>12)
  valid=false
elseif day<1 || day>max_days
    valid=false
else 
    valid=true
    
end

[Shikhar Srivastava]

function valid = valid_date(year,month,day)
if (mod(year,4)==0 || mod(year,400) ==0 && mod(year,100)~=0)
    if (month==2)
        valid = isscalar(date) && 0<date<30 && isscalar(year) &&year>0;
    elseif (1<=month<=12 && month~=2)
        valid = isscalar(date) && 0<date<=31 && isscalar(year) &&year>0;
    end
end
if (mod(year,4)~=0 || mod(year,400) ~=0 && mod(year,100)==0)
    if (month==2)
         valid = isscalar(date) && 0<date<=28 && isscalar(year) &&year>0;
    elseif (1<=month<=12 && month~=2)
        valid = isscalar(date) && 0<date<=31 && isscalar(year) &&year>0;
    end
end
end

please tell what is wrong

[Jan]

Please do not inject a question as a comment of an answer of another question. Open a new question instead.

The it is usful to mention, why you assume your code is wrong. You do have this important information already, so sharing it with the readers ist a good strategy.

One problem of your code: 0<date<30 will no do what you expect. This is evaluated from left to right. 0<date is either true or false, which are interpreted as 1 or 0. Both values are < 30 in every case. You want:

0 < date & date < 30

This appears multiple times in your code.

Another problem is that the variable valid is not defined under some conditions.

A hint to simplify the code: After:

if (month==2)

it is not need to test for month ~= 2 in the other branch:

elseif 1 <= month & month <= 12 %  not needed: && month~=2

Answer 5

[Nasir Rehman]

function valid= valid_date(year,month,day)

if isscalar(year) && isscalar(month) && isscalar(day)

if mod(year,400) == 0 || (mod(year,4) == 0 && mod(year,100) ~= 0)

if month==2 && (day>=1 && day<=29)

valid=true;

elseif (month == 1 || month == 3||month==5||month==7|| month == 8||month==10||month==12) && (day>=1 && day<=31)

valid=true;

elseif (month == 4 || month == 6 || month==9 || month==11) && (day>=1 && day<=30)

valid=true;

else

valid=false;

end

elseif month== 2 && (day>=1 && day<=28)

valid=true;

elseif (month == 1 || month == 3||month==5||month==7|| month == 8||month==10||month==12)&& (day>=1 && day <=31)

valid = true;

elseif (month == 4 || month == 6 || month==9 || month==11) && (day>=1 && day <=30)

valid=true;

else

valid =false;

end

else

valid =false;

end

[Rik]

Why did you post this answer? What does it teach? You're more than welcome to start answering questions, but why post a solution to a homework question without any explanation?

If you don't respond this answer will be deleted.

[Nasir Rehman]

Coding is not done using same approach always and i have done this through different way. It will mean alot for begginers like me to explore thinking approaches when building codes and I hope it will not bother you.

[Rik]

How exactly is this different from what already has been posted (apart from the missing formatting)?

If this answer is really meant for learners, how exactly is teaching anything? Where are the comments? Where is the documentation?

I also write code to explore ways to solve problems, I just don't post them every time I do. If you want to do that, Cody is a much better place.

I don't want to discourage you, but I also don't see the point of posting yet another solution to this homework question.

[Rik]

Yes and no. This platform is indeed meant for questions and answers. The thing to consider is the value of an answer.

There is a difference between a homework question and a non-homework question. The first is a teaching tool, so any answers posted here should be teaching tools as well. That is why your answer doesn't make sense. Did you post it as a teacher or as a student? If you posted it as a student you are posting it in the wrong place (this isn't a homework submission system), and if you posted it as a teacher your post confuses me (as it doesn't seem to teach anything the other answers already teach).

You might be interested in Cody. There you can solve questions and challenges. That platform doesn't care about any comments or duplicates. (note that to achieve the best scores there you will be encouraged to follow terrible coding practices)

[Rik]

What was so bad about your comment? I don't see why you would prefer to delete it.

You can (of course) disagree with my opinion. As you have replied, I will not delete this answer myself. I hope to convince you to delete it yourself and put your efforts into answering other questions. There are new questions every day, and everyone willing to help is welcome.

I am not affiliated with Mathworks in any way other than being a customer and a frequent contributor on Answers and the File Exchange. My main concern is keeping this forum clean and maximize the number of people receiving help.