Matlab String Input

To check data types of arguments in functions, and to assert they meet other criteria like array dimensions, and constraints on values, use validateattributes. It's very convenient, and standard matlab.

Unlike many languages, Matlab is dynamically typed. So there really is no way to tell Matlab that a function will always be called with a string input. If needed, you can check the type of the input at the beginning of a function, but that is not always the right answer. So, for example, in Java you may write something like this:

public class SomeClass {
    public static void someMethod(String arg1) {
        //Do something with arg1, which will always be a String
    }
}

In Matlab you have two options. First, you can write your code just assuming that it is a string, like this:

function someFunction(arg1)
%SOMEFUNCTION  Performs basic string operations
%    SOMEFUNCTION('INPUTSTRING')  performs an operation on 'INPUTSTRING'.

%Do something with arg1, which will always be a string.  You know 
%    this because the help section indicates the input should be a string, and 
%    you trust the users of this function (perhaps yourself)

Or, if you are paranoid and want to write robust code

function someFunction(arg1)
%SOMEFUNCTION  Performs basic string operations
%    SOMEFUNCTION('INPUTSTRING')  performs an operation on 'INPUTSTRING'.

if ~ischar(arg1)
    %Error handling here, where you either throw an error, or try 
    %    and guess what your user intended. for example
    if isnumeric(arg1) && isscalar(arg1)
        someFunction(num2str(arg1));
    elseif iscellstr(arg1)
        for ix = 1:numel(arg1)
            someFunction(arg1{1});
        end
    else
        error(['someFunction requires a string input.  ''' class(arg1) ''' found.'])
    end
else
    %Do somethinbg with arg1, which will always be a string, due to the IF statement
end