Parse Function Inputs
This example shows how to define required and optional inputs, assign defaults to optional inputs,
and validate all inputs to a custom function using the Input Parser.
The Input Parser provides a consistent way to validate and assign defaults to inputs, improving the
robustness and maintainability of your code. To validate the inputs, you can take advantage of
existing MATLAB functions or write your own validation routines.
Step 1. Define your function.
Create a function in a file named printPhoto.m. The printPhoto function has one required input
for the file name, and optional inputs for the finish (glossy or matte), color space (RGB or CMYK),
width, and height.
function printPhoto(filename,varargin)
In your function declaration statement, specify required inputs first. Use varargin to support
optional inputs.
Step 2. Create an inputParser object.
Within your function, call inputParser to create a parser object.
p = inputParser;
Step 3. Add inputs to the scheme.
Add inputs to the parsing scheme in your function using addRequired, addOptional, or
addParameter. For optional inputs, specify default values.
For each input, you can specify a handle to a validation function that checks the input and returns a
scalar logical (true or false) or errors. The validation function can be an existing MATLAB function
(such as ischar or isnumeric) or a function that you create (such as an anonymous function or a
local function).
In the printPhoto function, filename is a required input. Define finish and color as optional
inputs, and width and height as optional parameter value pairs.
defaultFinish = 'glossy';
validFinishes = {'glossy','matte'};
checkFinish = @(x) any(validatestring(x,validFinishes));
defaultColor = 'RGB';
validColors = {'RGB','CMYK'};
checkColor = @(x) any(validatestring(x,validColors));
defaultWidth = 6;
defaultHeight = 4;
addRequired(p,'filename',@ischar);
addOptional(p,'finish',defaultFinish,checkFinish)
addOptional(p,'color',defaultColor,checkColor)
addParameter(p,'width',defaultWidth,@isnumeric)
addParameter(p,'height',defaultHeight,@isnumeric)
Parse Function Inputs
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