#include "CLI/CLI.hpp" int main(int argc, char **argv) { CLI::App app("test for positional arity"); auto numbers = app.add_option_group("numbers", "specify key numbers"); auto files = app.add_option_group("files", "specify files"); int num1 = -1, num2 = -1; numbers->add_option("num1", num1, "first number"); numbers->add_option("num2", num2, "second number"); std::string file1, file2; files->add_option("file1", file1, "first file")->required(); files->add_option("file2", file2, "second file"); // set a pre parse callback that turns the numbers group on or off depending on the number of arguments app.preparse_callback([numbers](size_t arity) { if(arity <= 2) { numbers->disabled(); } else { numbers->disabled(false); } }); CLI11_PARSE(app, argc, argv); if(num1 != -1) std::cout << "Num1 = " << num1 << '\n'; if(num2 != -1) std::cout << "Num2 = " << num2 << '\n'; std::cout << "File 1 = " << file1 << '\n'; if(!file2.empty()) { std::cout << "File 2 = " << file2 << '\n'; } return 0; }