rgxg_utils_alternation(3) create regex that matches any of the given patterns


#include <rgxg/utils.h>
int rgxg_utils_alternation (const char **patterns, size_t size,
     char *regex, rgxg_options_t options);


rgxg_utils_alternation() generates the (extended) regular expression that matches any of the given patterns, an array of constant character strings. size specifies the number of entries of the array to use for the regular expression. Both patterns and its entries must be valid and not NULL for size>0.

Note that callers of rgxg_utils_alternation() which pass a non-constant 'char **' value as patterns need to use an explicit cast (i.e. '(const char**)') to avoid an incompatible pointer type warning.

The generated regular expression is written to the character string regex, including the terminating null byte ('\0'), unless RGXG_NONULLBYTE is set. If regex is NULL the return value is the number of characters (excluding the terminating null byte) that would have been written in case regex has been initialized. Note that the functions assume an arbitrarily long regex string, callers must ensure that the given string is large enough to not overflow the actual space.

options is either zero, or the bitwise-or of one or more of the following macros:

Omit the outer parenthesis, if any, of the regular expression.

Do not add the terminating null byte ('\0') to the regex string.


rgxg_utils_alternation() returns the number of characters (excluding the terminating null byte) written to regex.


This function is available since rgxg 0.1.


Hannes von Haugwitz <[email protected]>