How to add multiple if statements

So i was trying to do an age calculator, so i wanted it to detect strings and numerical value, then if it detected a string it will message that ' it is invalid', but if the inputed value is in numerical, but since im still on the days of the month i wanted to limit all value inputed below 31 days and if the user input greater than 31 it will also message an error. i already had progress with the code detecting if it is a string or number, but the problem is the detecting if the number inputed is below 31

So here is the code

function [day]=bdaycalcu
    disp ('What day did you born?');
    day= (' ');
    BdayDate= input (day, 's');
    
%this part detects if the user input a string or a value


    if ~isnan(str2double(BdayDate))
        %if the user input a value, it will also detect if it is below 31, if it is go to bmonthcalcu function
        bmonthcalcu;    
     
    %if the user input a string it will ask again 
    else
       disp('This is not a valid answer')
       bdaycalcu; 
       
    end
end

Answer 1

[Geoff Hayes]

Jan - I think that you just need to add a couple of conditions to your if statement. You would need to check that the input is numeric (which you are doing) AND is an integer (see isinteger) AND is greater than 0 AND less than our equal to 31. You can use a logical operator found here to AND your conditions.

[Jan Kyle Dismas]

i see its about logic, now i have a problem, because when i do this

function [day,a,b,c,d]=bdaycalcu
    disp ('What day did you born?');
    day= (' ');
    
    BdayDate= input (day, 's');
     a=(~isnan(str2double(BdayDate)));
     b=isinteger(BdayDate);
     c= a>0;
     d=a <= 31;
     

Since the collection of my values is in terms of strings 's', it would work with logic a since it detects wether theres is NaN which gives 0(false) if they see a string. however it would be a problem for logic b,c and d since the collection of my values would in terms of strings therefore wether i put a numerical or a string it will still give 0(false), is there any ways to get the numerical value out from the user input?

Appreciate your help btw

[Jan Kyle Dismas]

yo , nvm i kinda got it, in my previous comment i told that i could not get the numerical value from the input, because ~isnan only detect whether there is a string in the matrix, what i did is to make an variable and use the str2double(BdayDate)) to get the numerical value, isolating the ~isnan to another variable as my logic condition. thank you!!!

  % set logical condition
     day=(str2double(BdayDate));
     a= ~isnan(str2double(BdayDate));
     b= day > 0;
     c= day <= 31;