Classes
struct	Option
	Structure describing a single option. More...

Functions
int	getOption (int argc, char const argv, const char optstr, const Option longopts, int *idx)
	Get option character from command line argument list. More...

int	getOptionSingle (int argc, char const argv, const char optstr, const Option longopts, int *idx)
	Get option character from command line argument list and allow long-options with single-hyphens. More...

Variables
const char *	optarg
	On return from getOption() or getOptionSingle(), points to an option argument, if it is anticipated.

int	optind
	On return from getOption() or getOptionSingle(), contains the index to the next argv argument for a subsequent call to getOption() or getOptionSingle(). More...

int	optopt
	On return from getOption() or getOptionSingle(), saves the last known option character returned by getOption() or getOptionSingle(). More...

int	opterr
	Initialized to 1 and may be set to 0 to disable error messages.

int	optreset
	Must be set to 1 before evaluating the 2nd or each additional set of arguments.

Detailed Description

Command-line argument parsing. WARNING: THIS IS A PRIVATE NAMESPACE. NOT FOR PUBLIC CONSUMPTION.

This namespace provides a mechanism to parse command-line arguments and options for executables. It is identical in behavior to getopt_long functions available with many popular posix-platforms such as Darwin, FreeBSD and Linux. Virtually any OS which has getopt_long will adequately document this functionality. However, to avoid symbol ambiguity with the popular posix implementation, the following identifiers have been renamed:

getopt_long() -> getOption()
getopt_long_only() -> getOptionSingle()
option -> Option
option.has_arg -> Option.type

Function Documentation

◆ getOption()

int mp4v2::platform::prog::getOption	(	int	argc,
		char const	argv,
		const char *	optstr,
		const Option *	longopts,
		int *	idx
	)

Get option character from command line argument list.

getOption() is similar to posix getopt() but it accepts options in two forms: words and characters. The getOption() function provides a superset of the functionality of getopt(). The getOption() function can be used in two ways. In the first way, every long-option understood by the program has a corresponding short-option, and the Option structure is only used to translate from long-options to short-options. When used in this fashion, getOption() behaves identically to getopt(). This is a good way to add long-option processing to an esxisting program with a minimum of rewriting.

In the second mechanism, a long-option sets a flag in the Option structure structure passed, or will store a pointer to the command line argument in the Option structure passed to it for options that take arguments. Additionally, the long-option's argument may be specified as a single argument with an equal sign, eg:

myprogram --myoption=somevalue

When a long-option is processed, the call to getOption() will return 0. For this reason, long-option processing without shortcuts is not backwards compatible with getopt().

It is possible to combine these methods, providing for long-options processing with short-option equivalents for some options. Less frequently used options would be processed as long-options only.

Parameters

argc	number of arguments.
argv	argument array of strings.
optstr	string containing the following elements: individual characters, and characters followed by a colon to indicate an option argument is to follow. For example, an option string "x" recognizes an option "-x", and an option string "x:" recognizes an option and argument "-x argument".
longopts	array of Option entries. The last element must be filled with zeroes to indicate end-of-array.
idx	If not NULL, then the integer pointed to it will be set to the index of the long-option relative to longops.

Returns: If the flag field is NULL, val field is returned, which is usually just the corresponding short-option. If flag is not NULL, 0 is returned and val is stored in the location pointed to by flag field. A ':' will be returned if there was a missing option argument. A '?' will be returned if an unknown or ambiguous option was used. A -1 will be returned when the argument list has been exhausted.

◆ getOptionSingle()

int mp4v2::platform::prog::getOptionSingle	(	int	argc,
		char const	argv,
		const char *	optstr,
		const Option *	longopts,
		int *	idx
	)

Get option character from command line argument list and allow long-options with single-hyphens.

Behaves identically to getOption() with the exception that long-options may start with '-' in addition to '–'. If an option starting with '-' does not match a long option but does match a single-character option, the single-character option is returned.

Parameters

argc	number of arguments.
argv	argument array of strings.
optstr	string containing the following elements: individual characters, and characters followed by a colon to indicate an option argument is to follow. For example, an option string "x" recognizes an option "-x", and an option string "x:" recognizes an option and argument "-x argument".
longopts	array of Option entries. The last element must be filled with zeroes to indicate end-of-array.
idx	If not NULL, then the integer pointed to it will be set to the index of the long-option relative to longops.

Returns: If the flag field is NULL, val field is returned, which is usually just the corresponding short-option. If flag is not NULL, 0 is returned and val is stored in the location pointed to by flag field. A ':' will be returned if there was a missing option argument. A '?' will be returned if an unknown or ambiguous option was used. A -1 will be returned when the argument list has been exhausted.

Variable Documentation

◆ optind

int mp4v2::platform::prog::optind

On return from getOption() or getOptionSingle(), contains the index to the next argv argument for a subsequent call to getOption() or getOptionSingle().

Initialized to 1 and must be set manually to 1 prior to invoking getOption() or getOptionSingle() to evaluate multiple sets of arguments.

◆ optopt

int mp4v2::platform::prog::optopt

On return from getOption() or getOptionSingle(), saves the last known option character returned by getOption() or getOptionSingle().

On error, contains the character/code of option which caused error.

Classes

Functions