void setUsage(const char* usage);Set the usage message.
std::string getUsage() const;Get the usage message.
void setDescription(const char* description);Set the description in usage message.
const std::string& getDescription() const;Get the description message.
void setEpilog(const char* epilog);Set the epilog in usage message.
const std::string& getEpilog() const;Get the epilog message.
void setUsageWidth(std::size_t padWidth, std::size_t argsWidth, std::size_t sepWidth, std::size_t helpWidth);Set the usage witdhs.
args.setUsageWidth(2, 20, 2, 56); // default
args.setUsageWidth(2, 30, 2, 15);
args.setUsageWidth(1, 21, 1, 30);