Function main

examples/help_usage.cpp:10–46

#include <string>

int main(int argc, char **argv) {
    std::string input_file_name, output_file_name;
    int level{5}, subopt{0};

    // app caption
    CLI::App app{"CLI11 help"};

    app.require_subcommand(1);
    // subcommands options and flags
    CLI::App *const encode = app.add_subcommand("e", "encode")->ignore_case();  // ignore case
    encode->add_option("input", input_file_name, "input file")
        ->option_text(" ")
        ->required()
        ->check(CLI::ExistingFile);                                                               // file must exist
    encode->add_option("output", output_file_name, "output file")->option_text(" ")->required();  // required option
    encode->add_option("-l, --level", level, "encoding level")
        ->option_text("[1..9]")
        ->check(CLI::Range(1, 9))
        ->default_val(5);                                   // limit parameter range
    encode->add_flag("-R, --remove", "remove input file");  // no parameter option
    encode->add_flag("-s, --suboption", subopt, "suboption")->option_text(" ");

    CLI::App *const decode = app.add_subcommand("d", "decode")->ignore_case();
    decode->add_option("input", input_file_name, "input file")->option_text(" ")->required()->check(CLI::ExistingFile);
    decode->add_option("output", output_file_name, "output file")->option_text(" ")->required();

    // Usage message modification
    std::string usage_msg = "Usage: " + std::string(argv[0]) + " <command> [options] <input-file> <output-file>";
    app.usage(usage_msg);
    // flag to display full help at once
    app.set_help_flag("");
    app.set_help_all_flag("-h, --help");

    CLI11_PARSE(app, argc, argv);

    return 0;
}

/*
$ ./help_usage -h