What does the varargin function do and what does varargin{:} mean?

For example: [varargin{:}] = convertStringsToChars(varargin{:});

[Tommy]

varargin{:} creates a comma-separated list. On the right hand side of your example, the syntax is being used to create function call arguments. On the left hand side, it is being used to assign function return values (not concatenation, thanks Stephen!)

[Stephen23]

"On the left hand side, it is being used for concatenation."

This is incorrect: no arrays are being concatenated.

When used on the LHS it refers to the elements of the cell array, just like on the RHS. The only difference is that values are being assigned to those elements rather than extracted from them. This is explained in the section "Assigning to a Comma-Separated List" here:

https://www.mathworks.com/help/matlab/matlab_prog/comma-separated-lists.html#br2js35-8

[Tommy]

Somehow I missed this comment until now. Yikes, thank you for pointing out the mistake. Hopefully it is now correct.

Answer 1

[Stephen23]

"What does the varargin function do..."

varargin is not a function, it is a cell array which contains any number of optional input arguments:

https://www.mathworks.com/help/matlab/ref/varargin.html

"... and what does varargin{:} mean?"

That syntax creates a comma-separated list from the cell array varargin:

https://www.mathworks.com/help/matlab/matlab_prog/comma-separated-lists.html

https://www.mathworks.com/matlabcentral/answers/1656435-tutorial-comma-separated-lists-and-how-to-use-them

https://www.mathworks.com/company/newsletters/articles/matlab-tips-and-tricks-exploiting-the-comma-separated-list-vectorizing-cell-array-and-structure-references.html

So your example is equivalent to this:

[varargin{1},varargin{2},..,varargin{end}] = convertStringsToChars(varargin{1},varargin{2},..,varargin{end});

Answer 2

[KSSV]

varargin stands for variable number of arguments. You can input any number of arguments to the function. And these inputs are read by nargin which means the number of inputs.