re_comp or re_exec Subroutine

Purpose

Regular expression handler.

Library

Standard C Library (libc.a)

Syntax

char *re_comp( String)
const char *String;
int re_exec(String)
const char *String;

Description

Attention: Do not use the re_comp or re_exec subroutine in a multithreaded environment.

The re_comp subroutine compiles a string into an internal form suitable for pattern matching. The re_exec subroutine checks the argument string against the last string passed to the re_comp subroutine.

The re_comp subroutine returns 0 if the string pointed to by the String parameter was compiled successfully; otherwise a string containing an error message is returned. If the re_comp subroutine is passed 0 or a null string, it returns without changing the currently compiled regular expression.

The re_exec subroutine returns 1 if the string pointed to by the String parameter matches the last compiled regular expression, 0 if the string pointed to by the String parameter failed to match the last compiled regular expression, and -1 if the compiled regular expression was invalid (indicating an internal error).

The strings passed to both re_comp and re_exec subroutines may have trailing or embedded newline characters; they are terminated by nulls. The regular expressions recognized are described in the manual entry for the ed command, given the above difference.

Parameters

Item Description
String Points to a string that is to be matched or compiled.

Return Values

If an error occurs, the re_exec subroutine returns a -1, while the re_comp subroutine returns one of the following strings:

  • No previous regular expression
  • Regular expression too long
  • unmatched \(
  • missing ]
  • too many \(\) pairs
  • unmatched \)