function exclStrOrElemToChk = validateExclStrOrElemToChk(exclStrOrElemToChk, inputStr)

% Validate EXCLUDEDSTRINGS or ELEMENTSTOCHECK.

if matlab.internal.datatypes.isCharString(exclStrOrElemToChk) ... 

        || ((isvector(exclStrOrElemToChk) || isempty(exclStrOrElemToChk)) ... 

             && matlab.internal.datatypes.isCharStrings(exclStrOrElemToChk,true)) 

    % exclStrOrElemToChk is a (potentially empty) char vector or cellstr.

    exclStrOrElemToChk = string(exclStrOrElemToChk); 

elseif isnumeric(exclStrOrElemToChk) && isequaln(floor(exclStrOrElemToChk),exclStrOrElemToChk)

    % Assume exclStrOrElemToChk is checkElements intended to be a range or

    % linear indices into STRINGS.

    exclStrOrElemToChk = reshape(exclStrOrElemToChk, 1, []);

    if isempty(exclStrOrElemToChk)

        % Nothing to check for uniqueness.

        exclStrOrElemToChk = false(size(inputStr));

    elseif min(exclStrOrElemToChk) <= 0 || ~isreal(exclStrOrElemToChk) ...

           || any(isnan(exclStrOrElemToChk))

        % Elements of the range must be positive.

        error(message('MATLAB:makeUniqueStrings:NonPositiveRange'));

    elseif max(exclStrOrElemToChk) > numel(inputStr)

        % checkElements exceed the range of STRINGS number of elements.

        error(message('MATLAB:makeUniqueStrings:OutOfBoundRange'));

    end

elseif islogical(exclStrOrElemToChk)

    % Assume exclStrOrElemToChk is checkElements when exclStrOrElemToChk is

    % a logical array; the logical indices array must be the same length as

    % STRINGS.

    if ~isequal(numel(exclStrOrElemToChk), numel(inputStr))

        error(message('MATLAB:makeUniqueStrings:BadLengthLogicalMask'));

    end

elseif ~isstring(exclStrOrElemToChk)

    % Though they are useless here, <missing> string values are allowed.

    error(message('MATLAB:makeUniqueStrings:InvalidFirstOptionalArg'));

end 

end