regex.3

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)regex.3	8.1	9/11/90
.TH regex 3
.SH Name
re_comp, re_exec \- regular expression handler
.SH Syntax
.B char *re_comp(s)
.br
.B char *s;
.PP
.B re_exec(s)
.br
.B char *s;
.SH Description
The
.NXR "regex keyword"
.NXR "re_comp subroutine"
.NXR "re_exec subroutine"
.NXR "regular expression handler"
.PN re_comp
subroutine
compiles a string into an internal form suitable for pattern matching. 
The
.PN re_exec 
subroutine
checks the argument string against the last string passed to
.PN re_comp .
.PP
The
.PN re_comp
subroutine
returns 0 if the string
.I s
was compiled successfully; otherwise a string containing an
error message is returned. If 
.PN re_comp
is passed 0 or a null string, it returns without changing the currently
compiled regular expression.
.PP
The
.PN re_exec
subroutine returns 1 if the string
.I s
matches the last compiled regular expression, 0 if the string
.I s
failed to match the last compiled
regular expression, and \-1 if the compiled
regular expression was invalid (indicating an internal error).
.PP
The strings passed to both
.PN re_comp
and
.PN re_exec
may have trailing or embedded newline characters; 
they are terminated by nulls.
The regular expressions recognized
are described in the manual entry for 
.MS ed 1 ,
given the above difference.
.SH Diagnostics
The
.PN re_exec
subroutine returns \-1 for an internal error.
.PP
The
.PN re_comp
subroutine
returns one of the following strings if an error occurs:
.PP
.nf
.B "No previous regular expression"
.B "Regular expression too long"
.B "unmatched \e("
.B "missing ]"
.B "too many \e(\e) pairs"
.B "unmatched \e)"
.fi
.SH See Also
ed(1), ex(1), egrep(1), fgrep(1), grep(1)