CLI11/examples/positional_arity.cpp

#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](std::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;
}