args

args, an Octave code which demonstrates command line argument retrieval.

In particular, this is a demonstration of the NARGIN function, which counts command line arguments and the VARARGIN function, which allows the user to specify that a routine has a variable number of input arguments.

If a MATLAB function takes input arguments, such as

        function value = summit ( alpha, beta )

then there are two ways of supplying some or all the argument values when invoking the function.

We can call with commandline arguments:

        value = summit
        or
        value = summit 2
        or
        value = summit 2 4

or with functional arguments:

        value = summit ( )
        or
        value = summit ( 2 )
        or
        value = summit ( 2, 4 )

as long as the arguments are processed correctly.

In the commandline form, the arguments will be given to the function as character strings, which must be re-interpreted as numbers. A convenient way to allow the user to use either way of invoking the function requires that the function include a check as to the type of value it has been given. For example, to handle ALPHA, we might write

        if ( nargin < 1 )
          alpha = input ( 'Enter value of alpha: ' );
        elseif ( ischar ( alpha ) )
          alpha = str2num ( alpha );
        end

Licensing:

The computer code and data files made available on this web page are distributed under the MIT license

Languages:

args is available in a C version and a C++ version and a Fortran90 version and a MATLAB version and an Octave version and a Python version.

Related Programs and Data:

args_test

Source Code:

args.m, the source code;
summit.m, a function which will compute the sum of its two arguments. The function can be invoked using the commandline or functional form; some or all of the arguments may be omitted, in which case the function will request them.

Last revised on 20 June 2021.