This file contains GNU's externs/structs/prototypes. More...
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Classes | |
| struct | gk_option |
| The structure that stores the information about the command-line options. More... | |
Macros | |
| #define | no_argument 0 |
| #define | optional_argument 2 |
| #define | required_argument 1 |
Functions | |
| int | gk_getopt (int __argc, char **__argv, char *__shortopts) |
| Parse command-line arguments. More... | |
| int | gk_getopt_long (int __argc, char **__argv, char *__shortopts, struct gk_option *__longopts, int *__longind) |
| Parse command-line arguments with long options. More... | |
| int | gk_getopt_long_only (int __argc, char **__argv, char *__shortopts, struct gk_option *__longopts, int *__longind) |
| Parse command-line arguments with only long options. More... | |
Variables | |
| char * | gk_optarg |
| For communication arguments to the caller. More... | |
| int | gk_opterr |
| Controls error reporting for unrecognized options. More... | |
| int | gk_optind |
| Index in ARGV of the next element to be scanned. More... | |
| int | gk_optopt |
| Stores unknown option characters. More... | |
Detailed Description
This file contains GNU's externs/structs/prototypes.
- Date
- Started 3/27/2007
- Version
$Id: gk_getopt.h 10711 2011-08-31 22:23:04Z karypis $
Definition in file gk_getopt.h.
Macro Definition Documentation
◆ no_argument
| #define no_argument 0 |
Definition at line 49 of file gk_getopt.h.
◆ optional_argument
| #define optional_argument 2 |
Definition at line 51 of file gk_getopt.h.
◆ required_argument
| #define required_argument 1 |
Definition at line 50 of file gk_getopt.h.
Function Documentation
◆ gk_getopt()
Parse command-line arguments.
The gk_getopt() function gets the next option argument from the argument list specified by the argv and argc arguments. Normally these values come directly from the arguments received by main().
- Parameters
-
argc is the number of command line arguments passed to main(). argv is an array of strings storing the above command line arguments. options is a string that specifies the option characters that are valid for this program. An option character in this string can be followed by a colon (`:') to indicate that it takes a required argument. If an option character is followed by two colons (`::'), its argument is optional; this is a GNU extension.
- Returns
- It returns the option character for the next command line option. When no more option arguments are available, it returns -1. There may still be more non-option arguments; you must compare the external variable gk_optind against the
argcparameter to check this. -
If the option has an argument, gk_getopt() returns the argument by storing it in the variable gk_optarg. You don't ordinarily need to copy the gk_optarg string, since it is a pointer into the original
argvarray, not into a static area that might be overwritten. -
If gk_getopt() finds an option character in
argvthat was not included in options, or a missing option argument, it returns `?' and sets the external variable gk_optopt to the actual option character. If the first character of options is a colon (`:'), then gk_getopt() returns `:' instead of `?' to indicate a missing option argument. In addition, if the external variable gk_opterr is nonzero (which is the default), gk_getopt() prints an error message. This variable is set by gk_getopt() to point at the value of the option argument, for those options that accept arguments.
gk_getopt() has three ways to deal with options that follow non-options argv elements. The special argument `–' forces in all cases the end of option scanning.
- The default is to permute the contents of
argvwhile scanning it so that eventually all the non-options are at the end. This allows options to be given in any order, even with programs that were not written to expect this. - If the options argument string begins with a hyphen (`-'), this is treated specially. It permits arguments that are not options to be returned as if they were associated with option character `\1'.
- POSIX demands the following behavior: The first non-option stops option processing. This mode is selected by either setting the environment variable POSIXLY_CORRECT or beginning the options argument string with a plus sign (`+').
◆ gk_getopt_long()
| int gk_getopt_long | ( | int | argc, |
| char ** | argv, | ||
| char * | options, | ||
| struct gk_option * | long_options, | ||
| int * | opt_index | ||
| ) |
Parse command-line arguments with long options.
This function accepts GNU-style long options as well as single-character options.
- Parameters
-
argc is the number of command line arguments passed to main(). argv is an array of strings storing the above command line arguments. options describes the short options to accept, just as it does in gk_getopt(). long_options describes the long options to accept. See the defintion of gk_option for more information. opt_index this is a returned variable. For any long option, gk_getopt_long() tells you the index in the array long_optionsof the options definition, by storing it into*opt_index. You can get the name of the option withlongopts[*opt_index].name. So you can distinguish among long options either by the values in their val fields or by their indices. You can also distinguish in this way among long options that set flags.
- Returns
- When gk_getopt_long() encounters a short option, it does the same thing that gk_getopt() would do: it returns the character code for the option, and stores the options argument (if it has one) in gk_optarg.
- When gk_getopt_long() encounters a long option, it takes actions based on the flag and val fields of the definition of that option.
- If flag is a null pointer, then gk_getopt_long() returns the contents of val to indicate which option it found. You should arrange distinct values in the val field for options with different meanings, so you can decode these values after gk_getopt_long() returns. If the long option is equivalent to a short option, you can use the short option's character code in val.
- If flag is not a null pointer, that means this option should just set a flag in the program. The flag is a variable of type int that you define. Put the address of the flag in the flag field. Put in the val field the value you would like this option to store in the flag. In this case, gk_getopt_long() returns 0.
- When a long option has an argument, gk_getopt_long() puts the argument value in the variable gk_optarg before returning. When the option has no argument, the value in gk_optarg is a null pointer. This is how you can tell whether an optional argument was supplied.
- When gk_getopt_long() has no more options to handle, it returns -1, and leaves in the variable gk_optind the index in argv of the next remaining argument.
◆ gk_getopt_long_only()
| int gk_getopt_long_only | ( | int | argc, |
| char ** | argv, | ||
| char * | options, | ||
| struct gk_option * | long_options, | ||
| int * | opt_index | ||
| ) |
Parse command-line arguments with only long options.
Like gk_getopt_long(), but '-' as well as '–' can indicate a long option. If an option that starts with '-' (not '–') doesn't match a long option, but does match a short option, it is parsed as a short option instead.
Variable Documentation
◆ gk_optarg
| char* gk_optarg |
◆ gk_opterr
| int gk_opterr |
Controls error reporting for unrecognized options.
If the value of this variable is nonzero, then getopt prints an error message to the standard error stream if it encounters an unknown option character or an option with a missing required argument. This is the default behavior. If you set this variable to zero, getopt does not print any messages, but it still returns the character ? to indicate an error.
◆ gk_optind
| int gk_optind |
Index in ARGV of the next element to be scanned.
This variable is set by getopt to the index of the next element of the argv array to be processed. Once getopt has found all of the option arguments, you can use this variable to determine where the remaining non-option arguments begin.