Preventing too many function inputs

I am looking for a way to prevent a user from putting in too many inputs for a function. Here is a quick code example:

exfunction(1,3,9)
function exfunction(x,y,z)
    switch nargin %Checking # arguements
        case 3 %3 function arguements
            a=x+y;  %Adds x and y
            b=x*z;  %Multiplies x and z
            disp([a,b]); %Displays a and b
        otherwise %Less than 3 function arguements (Doesn't work for more than 3)
            disp('Wrong Number of Arguements')
    end %End switch
end %End function

This function has 3 inputs: x, y, and z. If the user were to only define x and y, it would display "Wrong Number of Arguements" without issue. However, if the user added 4, 5, or any number over the 3 variables, MatLab tries to define the variable (which doesn't exist) and gives me an error.

Any help is appreciated, thanks!

Answer 1

[per isakson]

>> exfunction(1,3,9,4,5)

throws the error

Error using exfunction
Too many input arguments. 

I assume that's the error you encounter and that you want it to handle the situation more gracefully.

Replace

function exfunction(x,y,z)

by

function exfunction( varargin )
    
    if nargin >= 3
        disp( 'Too many input arguments. Three anticipated' )
        return
    else
        x = varargin{1};
        y = varargin{2};
        z = varargin{3};
    end

Now

>> exfunction(1,3,9,4,5)

will display

Too many input arguments. Three anticipated

[Samuel Brewton]

Varargin turns out to be exactly what I needed. Thank you!

[per isakson]

I guess you discovered my error

nargin >= 3

should be

nargin >= 4

[Stephen23]

Note:

• using varargin means you will not get useful, meaningful information via tab completion or function hinting.
• Throwing an error is the standard, easy way to handle this. If incorrrect inputs are provided, why let the code continue? This indicates a syntax problem that need to be fixed, not ignored.

Is there a particular reason why throwing an error does not work for you?