isnumber?

[mark b.]

hi, i cannot find anything in matlab-help to check if smth
is a number. i need to compare if user wrote a number or a
letter.

if i try 'isnumeric' it doesn't work as i want to. for
isnumeric(1) and isnumeric(a) it returns true..

is there smth similar to isnumber in matlab?

[Walter Roberson]

In article <fqek97$s4a$1...@fred.mathworks.com>,

mark b. <john.do...@mathworks.com> wrote:
>hi, i cannot find anything in matlab-help to check if smth
>is a number. i need to compare if user wrote a number or a
>letter.

ischar() to test for characters.

See also isfinite() and isnan()
--
"All human knowledge takes the form of interpretation."
-- Walter Benjamin

[Dave Bell]

In your examples, <1> is a numeric constant, and test as numeric.
But <a> is the name of a variable, that probably *contains* a numeric value.
If you try isnumeric('a'), you'll see it returns 0.
Further, a='abc'; isnumeric(a) will return 0,
while b=123; isnumeric(b) will return 1.

But be careful how you have the user enter the text.
If you do, c='123'; isnumeric(c) will return 0, because <c> contains a
string that just happens to be all digits; it is not a number!

Dave

[mark b.]

thx!

[hello_e...@arcor.de]

since this still comes up pretty close to top in google, here is another and quite functional approach: try matlab regexp.

for example for only digits you can try pattern /\d+/

[Paulo Abelha]

"mark b." <john.do...@mathworks.com> wrote in message <fqek97$s4a$1...@fred.mathworks.com>...

I've coded a function that my help:

http://uk.mathworks.com/matlabcentral/fileexchange/59167-checkissinglenumber--n--/content/CheckIsSingleNumber.m


Best,

[Benjamin Askelund]

Hi there, this might help you out. I made a short code that takes in a number (or string) from a user and returns the number if it sure is a number or 0 if it is a string.

copy and paste in a "script" to try out. Save the script and then test it in comand window.


CODE:

number = input('Type a number please = ', 's');
% this pice of code can take in both numbers or strings:

number = str2num(number);
%If the string "number" does not represent a valid number or matrix,
str2num(number) returns the empty matrix.

if isempty(number)
answer = 0;
else
answer = daysInMonth(number);
end

disp(answer)

ENDCODE

or:


number = input('Type a number please = ', 's');
number = str2num(number);

if isempty(number)
disp('You wrote a text')
else
fprintf(' You wrote the number %2.0f\n ', number)
end