CODEWITHSUNDEEP
matlab
Novice_Developer
Novice_Developer

Reputation: 1492

Check for existence of variable argument input

It takes variable number of arguments but how can i check if a particular variable argument exists like for example varargin{2} , So far I have tried using exist but maybe I am not using it correctly 

function vatest(testindex,varargin)

if (exist('varargin{1}','var'))
    disp('oneexist')
else if (exist('varargin{2}','var'))
     disp('twoexist')
    end
end

like for example vatest(1,2,3) should output

twoexist

NOTE: I am already using nargin to get the number of inputs ,but please suggest something else than that

UPDATE: Explanation for not using a nargin

lets suppose I have a test function as above 

function vatest(testindex,textindex2,textindex3,varargin)

and it does some something like 

if nargin >3 
%%do something 
if nargin >4
%%do something 
if nargin >5 
%%do something 
if nargin >6 
%%do something 
if nargin >7 
%%do something 
if nargin >8 
%%do something

and for some reason I no longer need testindex3 in the input then I have to change condition for all the if conditionsI hope it clarifies

Upvotes: 3

Views: 2686

Answers (2)

Stewie Griffin
Stewie Griffin

Reputation: 14939

YEY I finally got to use the sexist function:

function vatest(testindex,varargin)

values = {'zero','one','two', 'three', 'four'};
fprintf('%sexist',values{numel(varargin)})
end

For some reason, you didn't want a space between "one" and "exist". So, this should do what you specified (but not necessarily what you want).

On a more serious note, I suggest switch:

function vatest(testindex, varargin)

num_argin = numel(varargin);
fprintf('%d inputs', num_argin);

switch num_argin
    case 1
        % Some code
    case 2
        % Some code
    case 3
        % Some code
    otherwise
        % Some code

Upvotes: 1

Suever
Suever

Reputation: 65460

varargin is simply a cell array containing the inputs. Therefore, you can determine how many inputs were provided by testing it's length: numel(varargin).

exist is not really designed for this and is likely going to be much slower than simply determining the length of a known variable.

nInputs = numel(varargin)

if nInputs > 1
    disp('More than 1 input')
elseif nInputs > 0
    disp('Only 1 input')
else
    disp('No inputs')
end

Or more simply:

fprintf('%d inputs\n', numel(varargin));

Upvotes: 4

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