#include "argparse/argparse.hpp"

int main(int argc, char **argv) {

  // A parser object
  argparse::Parser p;

  // Program data corresponding to flags, options, and positional arguments
  bool verbose = false;
  std::string toPrint;
  std::string maybePrint;
  int repeats = 1;

  // Inform the parser of the program data. It will do type-specific conversion
  // from string.

  // An option invoked with `--repeat N`
  p.add_option(repeats, "--repeat");
  // A flag invoked with `--verbose` or `-v`
  p.add_flag(verbose, "--verbose", "-v");
  // a required positional argument (position 1)
  p.add_positional(toPrint)->required();
  // an optional positional argument (position 2)
  auto psnl = p.add_positional(maybePrint);

  // If there was an error during parsing, report it.
  if (!p.parse(argc, argv)) {
    std::cerr << p.help();
    exit(EXIT_FAILURE);
  }

  // Execute the program logic
  if (verbose) {
    std::cerr << "about to print '" << toPrint << "' " << repeats << " times";
    if (psnl->found()) {
      std::cerr << ", then '" << maybePrint << "'";
    }
    std::cerr << std::endl;
  }

  for (int i = 0; i < repeats; ++i) {
    std::cout << toPrint;
  }
  if (psnl->found()) {
    std::cout << maybePrint;
  }
  std::cout << std::endl;

  return 0;
}

Adding Options

Options may be int, size_t, float, double, or std::string and currently support long strings. They are invoked like --long-opt value (not --long-opt=value).

argparse::Parser p;
p.add_option(var1, "--long-opt")

Adding Flags

Flags are always bools, and currently support long or short strings. The boolean variable is ALWAYS set to true if the flag is found. They are invoked like --long-flag (not --long-flag=true or --long-flag true).

argparse::Parser p;
p.add_option(flag1, "--long-flag")
p.add_option(flag2, "--antother-flag", "-s");

Positional Arguments

Positional arguments are added in order. Positional arguments are optional by default. Use required() to require them. add_positional() returns a PosnlBase * that may be queried with found() to see if an optional positional argument was found.

argparse::Parser p;
p.add_positional(var1)->required();
auto something = p.add_positional(var2);
if (something->found()) {
  // var2 was set
}

Anything after -- is considered a positional argument, unless -- follows an option. Here, the first -- is the value for --option and will be in s1. The second -- marks the beginning of positional arguments. and the string aa will be in s2.

argparse::Parser p;
std::string s1, s2;
p.add_option(s1, "--option");
p.add_positional(s2);
std::cerr << s1;
std::cerr << s2;

$ ./myexe --option -- -- aa
--aa

Parsing

argparse::Parser p;
// set up flags, arguments, and options
p.parse(argc, argv);

parse() returns something falsy if there is an error. Parsing modifies argc and argv to remove consumed options by default. To disable, call p->no_consume(). Parsing will silently skip unrecognized arguments. To error instead, call p->no_unrecognized().

Features

Does not require std::regex
allow (default) / disallow (Parser::no_unrecognize()) unrecognized options and flags
optional/required (PosnlBase::required()) positional arguments
flags with -s, --long-flag formats
options with --long-opt val format
positional arguments
-- to stop parsing options and flags
modify argc/argv (disable with Parser::no_consume())
Option/Positional Argument Types
- int
- size_t
- float
- double
- std::string

Roadmap

Reject duplicate flags / options at run time
Support short option strings
Help string output
support --long-option=value
have the last positional argument fill a vector with remaining