I am looking for a code to identify if the entered number is odd or even. For example: "ABC 123", I would be really grateful if someone shares the code.

I tried using mod function but it doesn't work as my input contains Alphabet and numbers both.

Answer 1

[Paolo]

You need to remove the characters before using mod function. You can use regexp to remove all non digits characters.

The following code uses regexp to match digits only in variable t , with the expression '\d' . The indices returned by regexp functions are used to get the digit values, before converting them to a number with num2str.

    t = "ABC123";
    t = char(t);

    num = str2num(t(regexp(t,'\d')));

    if(~mod(num,2))
        disp('Number is even')
    else
        disp('Number is odd')
    end

[Stephen23]

@Paolo: Note that str2num is basically a wrapper for eval, which is why most experienced users on this forum would recommend to avoid it:

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

str2num can often be replaced by str2double, or more efficient parsing with sscanf.

str2double(regexp(t,'\d+','match','once'));

[Paolo]

Thank you Stephen. I did not know that str2num used eval, so thanks for pointing that out. I actually have already read that post of yours; it's really informative and well written.

That's true, Matlab always recommends using str2double, which is slightly counter-intuitive in my opinion because why would I need to convert to a double if I do not require the precision? I guess the reason is the eval call of str2num as you pointed out.

[Stephen23]

@Paolo: instances of eval will hinder JIT optimization, so I suspect that efficiency might be the main reason for the documentation's advice to avoid str2num. This might be interested to you:

https://www.mathworks.com/matlabcentral/answers/357420-how-to-convert-a-numeric-string-into-a-numeric-range

Answer 2

[Stephen23]

sscanf is probably the most efficient way to convert that char vector into a numeric:

>> sscanf('ABC 123','%*s %d')
ans =  123

[Paolo]

sscanf is efficient, however if the input differs from 'ABC 123' and is rather '123 ABC 123', you will need to change the conversion specifiers.

[Stephen23]

@Paolo: yes, the format string does need to be tailored to the actual expected strings, the exact format of which is something that Mazhar will have to clarify for us.

[Mazhar]

Well, I used the answer by @Paolo and it works perfectly fine for me. Thankyou guys.