Input is a valid integer

How to check if the value entered by the user is a valid integer and not a negative number(such as -1,-9,-10 etc) or characters/strings(such as a, i,thank you)or special symbols(such as @,* etc) and also that is not equal to 0?

Answer 1

[Walter Roberson]

https://www.mathworks.com/matlabcentral/newsreader/view_thread/163080

[omri dagan]

it's a broken link

Answer 2

[DGM]

Assuming the input x is a char vector from input() which represents a numeric scalar:

isvalidnumber('56') % positive scalar integer is okay

ans = logical
   1

isvalidnumber('-56') % not valid (not positive)

ans = logical
   0

isvalidnumber('56.2') % not valid (noninteger)

ans = logical
   0

isvalidnumber('[56 23]') % not valid (nonscalar)

ans = logical
   0

isvalidnumber('asdf') % not valid (non-numeric)

ans = logical
   0

isvalidnumber('56E3') % E-notation is valid (56000 is a positive scalar integer)

ans = logical
   1

function isvalid = isvalidnumber(x)
    x = str2double(x); % NaN if text or nonscalar numeric
    isvalid = (x > 0) & (mod(x,1) == 0); % true only for positive integers
end

There are probably other ways to approach this, but it's a basic start. If you really want to improve things, take a step back and stop designing around accumulating parameters interactively via input().