cxxargs

Yet another C++11 header-only command line parsing library. Heavily inspired by the cxxopts library, which you might want to consider using.

Accepted input

cxxargs will recognize command line arguments and options supplied in the following formats

--long-name
--long-name=value
--long-name value

-a
-ab
-abc value

where the last option will take the argument 'value', while -a and -b do not.

Anything after -- will be parsed as positional arguments (vector of strings in the supplied order). Unrecognized arguments before -- will be ignored.

Usage

Simply drop the header file in your includes and add it to your project

#include "cxxargs.hpp"

Example

Create a cxxargs::Arguments object

cxxargs::Arguments args("cxxargs command line parser", "Usage:
myprogram -d 0.5483 --toggle --list=1,2,3,4 -- positional1, positional2");

and define some possible arguments

  args.add_argument<double>('d', "double", "This is a double with the
  default value 0.222.", 0.222);
  args.add_long_argument<bool>("toggle", "This is a boolean toggle with
  the default value false.");
  args.add_short_argument<std::vector<int>>('l', "This is a list of
  integers with no default values.");

All arguments with no defaults are required and must be supplied from the command line.

Parse the command line input

myprogram --double=0.5483 --toggle -l 1,2,3,4 -- positional1, positional2

by calling

args.parse(argc, argv);

which will set the value of the double to 0.5483, switch the toggle to true, create a vector of integers containing the values { 1, 2, 3, 4 }, and parse the positional arguments positional1 and positional2 into a vector of strings { "positional1", "positional2" }.

args.help() can be called

std::cout << args.help() << std::endl;

to print the help message

Usage: myprogram -d 0.5483 --toggle --list=1,2,3,4 -- positional1, positional2"
-d --double	This is a double with the default value 0.222.
-t --toggle	This is a boolean toggle with the default value false.
-l --list	This is a list of integers with no default values.

Parsed values can be accessed using

args.value<double>("double");

the value() function will throw an exception if 1) the argument was defined without a default value and a value was not supplied to parse(), or 2) the argument "double" has not defined as a possible argument.

Extensions

cxxargs can easily be extended to interpret the command-line input as something unconvential. For example, to open the argument '-f infile.txt' as a std::shared_ptr to a std::ifstream for reading, start by defining a std::istream& operator>> for this particular class in the cxxargs namespace

namespace cxxargs {
  std::istream& operator>> (std::istream &in, std::shared_ptr<std::ifstream> &t) {
    std::string filename;
    in >> filename;
    t = std::shared_ptr<std::ifstream>(new std::ifstream(filename));
    return in;
  }
}

and use the same syntax as before to add the file into the list of possible arguments

args.add_argument<std::shared_ptr<std::ifstream>>('f', "infile", "This is an infile stream.");

Requirements and dependencies

This is a header-only library with no dependencies, only requiring that your compiler supports C++11.

License

The source code from this project is subject to the terms of the Mozilla Public License, v. 2.0. A copy of the MPL is supplied with the project, or can be obtained at https://mozilla.org/MPL/2.0/.