string that may or may not need to be converted to num...

I am bringing a string into a function. I need to convert it to num ONLY if it's intended as a number like 2, 40, 100... but when the user enters it as something else, leave it as a string. Can that be done?

Thanks!

Answer 1

[Bish Erbas]

Yes. Take a look at the function below:

str2num

https://www.mathworks.com/help/matlab/ref/str2num.html

Edit: OP clarified their question and one way to accomplish what they need would be using the following function:

https://www.mathworks.com/matlabcentral/fileexchange/52925-words-to-number

Edit2: Use str2double instead. See comments section for details.

https://www.mathworks.com/help/matlab/ref/str2double.html

[David Pesetsky]

No... that doesn't leave the string alone if it's actually a string..

>> str2num('2')

ans =

     2

>> str2num('two')

ans =

     []

[Bish Erbas]

I see. That part wasn't clear in your question. Try this:

https://www.mathworks.com/matlabcentral/fileexchange/52925-words-to-number

[Stephen23]

Note that str2double is preferred over str2num, because str2num is a wrapper around eval, with all of its inherent disadvantages.

[Bish Erbas]

@Stephen Cobeldick is absolutely right. Thanks for the helpful reminder. Old habits die hard. I gotta learn to remember using the more efficient str2double

[Walter Roberson]

s = 'two';

t = str2double(s);
if isnan(t); t = s; end

Answer 2

[Walter Roberson]

str2double() and test for nan, keep the original if you got nan.