HP 3000 Manuals HP 3000 Manuals
regcomp
Compile a regular expression.
Syntax
#include <regex.h>
int regcomp (regex_t *reg, const char *regstr, int flags);
Parameters
reg points to an object where regcomp() stores the compiled
regular expression. regex_t is defined in <regex.h>.
regstr points to the regular expression as a string (the way it
might be specified for a command like grep).
flags gives a variety of flags for the compilation. Flags are
given by symbols defined in <regex.h> which can be ORed
together. The recognized symbols are:
REG_EXTENDED uses extended regular expressions
(see regexp(3)). The default is
to interpret regstr as a basic
regular expression.
REG_ICASE ignores the case of letters in
matches. The setting of LC_CTYPE
affects which characters are
considered to be opposite cases
of each other.
REG_NEWLINE treats the newline character as a
regular character, without its
special meaning.
REG_NOSUB indicates that regcomp() should
only report success or failure,
and not set reg->re_nsub (see the
following section). It also
affects the behavior of
regexec(3)
Return Values
0 Successful compile
Error Not successful compile
code
Description
regcomp() compiles a regular expression for later use. Early
implementations of regcomp() generated executable code that determined
whether or not strings matched regstr. Under POSIX.2, regcomp() may
generate executable code and/or data which speeds pattern-matching. The
result of regcomp() is a structure of the regex_t type which is stored in
reg. This structure type contains at least the following field:
size_t is usually set to the number of parenthesized subexpressions
re_nsub found in regstr. These subexpressions are delimited with
\(\)
in basic regular expressions and
()
in extended regular expressions. regcomp() does not set
re_nsub if REG_NOSUB is turned on in flags.
Errors
If regcomp() successfully compiles regstr it returns zero; otherwise, it
returns one of the following symbolic values:
REG_BADBR CAUSE The contents of
\{\}
were invalid: not a number, too large a number, more
than two numbers, first number larger than second.
ACTION Make sure that the contents of \{\} or {} are valid.
Table 4-0. (cont.)
REG_BADPAT CAUSE regstr was an invalid regular expression.
ACTION Specify a valid regular expression
REG_BADRPT CAUSE regstr contained a ?, *, or + that was not preceded
by a valid regular expression.
ACTION Make sure that every unquoted /, *, or + in regstr is
preceded by a valid regular expression.
REG_EBRACE CAUSE regstr contained a \{\} imbalance.
ACTION Make sure that all { and } characters and all \{ and
\} characters appear in matched pairs in regstr.
REG_EBRACK CAUSE regstr contained a [] imbalance.
ACTION Make sure that all [ and ] characters appear in
matched pairs in regstr.
REG_ECOLLATE CAUSE regstr contained a reference to an invalid collating
element.
ACTION Make sure that all collating elements referenced in
regstr are valid in the locale indicated by
LC_COLLATE.
REG_ECTYPE CAUSE regstr contained a reference to an invalid character
class.
ACTION Make sure that all character classes referenced in
regstr are valid in the locale indicated by LC_CTYPE.
REG_EESCAPE CAUSE regstr contained a trailing \.
ACTION Remove the trailing \ or complete the escape
sequence.
REG_ENEWLINE CAUSE A newline was found before the end of a pattern, and
the REG_ENEWLINE flag was not set.
ACTION Set the REG_ENEWLINE flag, or check the pattern for a
missing /.
REG_EPAREN CAUSE regstr contained a () or \(\) imbalance.
ACTION Make sure that all ( and ) characters and all \( and
\) characters appear in matched pairs in regstr.
Table 4-0. (cont.)
REG_ERANGE CAUSE A range expression contained an invalid endpoint.
For example, an equivalence or character class is not
valid.
ACTION Specify a valid endpoint.
REG_ESPACE CAUSE There were not enough free system resources for
regcomp() to compile regstr
ACTION Free up more resources or specify a less complex
regular expression.
REG_ESUBREG CAUSE The number in a \number construct was greater than
the number of matching subexpressions.
ACTION Make sure that number is less than or equal to the
number of matching subexpressions.
REG_EFATAL CAUSE An internal error occurred.
ACTION Contact your system manager.
See Also
grep(1), regexec(), regfree(), regexp(3)