getopt_wrapper Class Reference

A wrapper for parsing command-line options using getopt and getopt_long. More...

#include <getopt_wrapper.hpp>

Inheritance diagram for getopt_wrapper:

Classes
struct	option_with_desc
	Extension of struct option that includes a description string. More...

Public Member Functions
	getopt_wrapper (std::string usage_str, std::vector< option_with_desc > long_opts)
	Constructs a getopt_wrapper object for parsing command-line options.
void	print_usage (std::ostream &os)
	Prints the program usage and all available options to a stream.

Protected Attributes
std::vector< option >	long_options_
	Storage of long options for getopt parsing.
std::vector< option_with_desc >	opts_
	Original option definitions with descriptions.
std::string	usage_str_
	Program usage/help string.
std::string	short_opt_string_
	Concatenated short option string.
std::size_t	max_long_opt_length_ = 0
	Maximum long option length.

Detailed Description

A wrapper for parsing command-line options using getopt and getopt_long.

This class simplifies handling both short and long command-line options, automatically generating the short option string and formatting help output.

The class provides:

• option_with_desc: A structure extending struct option to include a description string for help messages.
• Storage for long options (long_options_) and original option definitions (opts_).
• The program usage string (usage_str_) and the generated short option string (short_opt_string_).
• Tracking of the maximum long option length (max_long_opt_length_) for nicely aligned help output.

Constructor & Destructor Documentation

getopt_wrapper()

getopt_wrapper::getopt_wrapper ( std::string usage_str, std::vector< option_with_desc > long_opts )

inline

Constructs a getopt_wrapper object for parsing command-line options.

This constructor initializes both short and long options for use with getopt and getopt_long. It sets up internal data structures for option parsing and generates the short option string automatically.

Parameters

usage_str	A string describing the program usage, typically displayed when the user requests help.
long_opts	A vector of option_with_desc structures describing long options, their short equivalents, argument requirements, and descriptions.

The constructor performs the following steps:

1. Moves the usage string and option vector into member variables.
2. Resizes the internal long_options_ array to accommodate all options plus a terminating zeroed element (required by getopt_long).
3. Copies each option from opts_ into long_options_.
4. Updates max_long_opt_length_ to track the length of the longest long option name (used for formatting help output).
5. Builds the short option string short_opt_string_:
   • Adds the short option character if val is set.
   • Appends : if the option requires an argument (required_argument).

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Member Function Documentation

print_usage()

void getopt_wrapper::print_usage ( std::ostream & os )

inline

Prints the program usage and all available options to a stream.

This function formats and displays the usage string followed by a nicely aligned list of command-line options and their descriptions. Both short and long options are displayed if available.

Parameters

os	The output stream to which the usage information is written (e.g., std::cout or std::cerr).

The method performs the following steps:

1. Prints the main usage string (usage_str_) followed by a blank line.
2. Iterates over all options in opts_.
3. For each option with a description:
   • Prints the short option (if printable) prefixed with -.
   • Prints the long option name (if present) prefixed with --.
   • Aligns descriptions based on the longest long option (max_long_opt_length_) for a clean, columnar format.
4. Flushes the output stream to ensure all text is written.

Example output:

Usage: myprogram [options]
 
 -h, --help        Display this help message
 -v, --version     Show version information

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Member Data Documentation

long_options_

std::vector<option> getopt_wrapper::long_options_

protected

Storage of long options for getopt parsing.

This vector holds the struct option objects used by getopt_long. It is automatically populated based on the provided option_with_desc definitions.

max_long_opt_length_

std::size_t getopt_wrapper::max_long_opt_length_ = 0

protected

Maximum long option length.

Used when formatting help output so that all descriptions are aligned to the same column, regardless of option name length.

opts_

std::vector<option_with_desc> getopt_wrapper::opts_

protected

Original option definitions with descriptions.

This vector stores the extended option structures (option_with_desc), which include descriptions for generating nicely formatted help/usage messages.

short_opt_string_

std::string getopt_wrapper::short_opt_string_

protected

Concatenated short option string.

Generated automatically from the provided options. This string is passed to getopt() for parsing short options (e.g., "hv:o:").

usage_str_

std::string getopt_wrapper::usage_str_

protected

Program usage/help string.

Contains a short description of the program usage, typically displayed at the top of the --help output.

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The documentation for this class was generated from the following file:

• src/getopt_wrapper.hpp