inputParser does not throw error

I want to check, whether an input is a string. Why does it not work?

p = inputParser() ;
isString = @(x) (isvector(x) | isempty(x)) & ischar(x) ;
addParameter(p, 'property_name', isString) ;

isString(13)  % yields False

parse(p, 'property_name', 13)  % Throws no error

Answer 1

[Matt J]

The validation function should be the 4th argument,

addParameter(p, 'property_name','', isString) ;