< cpp‎ | regex
Defined in header <regex>
typedef /*unspecified*/ match_flag_type;

constexpr match_flag_type match_default = 0;
constexpr match_flag_type match_not_bol = /*unspecified*/;
constexpr match_flag_type match_not_eol = /*unspecified*/;
constexpr match_flag_type match_not_bow = /*unspecified*/;
constexpr match_flag_type match_not_eow = /*unspecified*/;
constexpr match_flag_type match_any = /*unspecified*/;
constexpr match_flag_type match_not_null = /*unspecified*/;
constexpr match_flag_type match_continuous = /*unspecified*/;
constexpr match_flag_type match_prev_avail = /*unspecified*/;
constexpr match_flag_type format_default = 0;
constexpr match_flag_type format_sed = /*unspecified*/;
constexpr match_flag_type format_no_copy = /*unspecified*/;

constexpr match_flag_type format_first_only = /*unspecified*/;

match_flag_type is a BitmaskType that specifies additional regular expression matching options.

[edit] Constants

Note: [first, last) refers to the character sequence being matched.

Constant Explanation
match_not_bol The first character in [first,last) will be treated as if it is not at the beginning of a line (i.e. ^ will not match [first,first)
match_not_eol The last character in [first,last) will be treated as if it is not at the end of a line (i.e. $ will not match [last,last)
match_not_bow "\b" will not match [first,first)
match_not_eow "\b" will not match [last,last)
match_any If more than one match is possible, then any match is an acceptable result
match_not_null Do not match empty sequences
match_continuous Only match a sub-sequence that begins at first
match_prev_avail --first is a valid iterator position. When set, causes match_not_bol and match_not_bow to be ignored
format_default Use ECMAScript rules to construct strings in std::regex_replace (syntax documentation)
format_sed Use POSIX sed utility rules in std::regex_replace. (syntax documentation)
format_no_copy Do not copy un-matched strings to the output in std::regex_replace
format_first_only Only replace the first match in std::regex_replace

All constants, except for match_default and format_default, are bitmask elements. The match_default and format_default constants are empty bitmasks

[edit] Notes

In C++11, these constants were specified with redundant keyword static, which was removed by C++14 via LWG issue 2053

[edit] See also

attempts to match a regular expression to an entire character sequence
(function template)
general options controlling regex behavior
describes different types of matching errors