Using sub-commands in slash commands

This demonstrates how to use sub-commands within slash commands. Also shown below is an example of how to get a "resolved" parameter without having to use the cache or an extra API call.

#include <dpp/dpp.h>
#include <iostream>
 
int main() {
 
    dpp::cluster bot("token");
 
    bot.on_log(dpp::utility::cout_logger());
 
    /* Executes on ready. */
    bot.on_ready([&bot](const dpp::ready_t & event) {
        if (dpp::run_once<struct register_bot_commands>()) {
            /* Define a slash command. */
            dpp::slashcommand image("image", "Send a specific image.", bot.me.id);
            image.add_option(
                /* Create a subcommand type option for "dog". */
                dpp::command_option(dpp::co_sub_command, "dog", "Send a picture of a dog.").
                add_option(dpp::command_option(dpp::co_user, "user", "User to turn into a dog.", false))
            );
            image.add_option(
                /* Create another subcommand type option for "cat". */
                dpp::command_option(dpp::co_sub_command, "cat", "Send a picture of a cat.").
                add_option(dpp::command_option(dpp::co_user, "user", "User to turn into a cat.", false))
            );
            /* Create command */
            bot.global_command_create(image);
        }
    });
 
    /* Use the on_slashcommand event to look for commands */
    bot.on_slashcommand([&bot](const dpp::slashcommand_t & event) {
        dpp::interaction interaction = event.command;
        dpp::command_interaction cmd_data = interaction.get_command_interaction();
        /* Check if the command is the image command. */
        if (interaction.get_command_name() == "image") {
            /* Get the sub command */
            auto subcommand = cmd_data.options[0];
            /* Check if the subcommand is "dog" */
            if (subcommand.name == "dog") { 
                /* Checks if the subcommand has any options. */
                if (!subcommand.options.empty()) {
                    /* Get the user from the parameter */
                    dpp::user user = interaction.get_resolved_user(
                        subcommand.get_option<dpp::snowflake>(0)
                    );
                    event.reply(user.get_mention() + " has now been turned into a dog."); 
                } else {
                    /* Reply if there were no options.. */
                    event.reply("No user specified");
                }
            }
            /* Check if the subcommand is "cat" */
            if (subcommand.name == "cat") {
                /* Checks if the subcommand has any options. */
                if (!subcommand.options.empty()) {
                    /* Get the user from the parameter */
                    dpp::user user = interaction.get_resolved_user(
                        subcommand.get_option<dpp::snowflake>(0)
                    );
                    event.reply(user.get_mention() + " has now been turned into a cat."); 
                } else {
                    /* Reply if there were no options.. */
                    event.reply("No user specified");
                }
            }
        }
    });
 
    bot.start(dpp::st_wait);
    
    return 0;
}