regerror - Return Error Message for Regular Expression

Syntax

#include <sys/types.h>
#include <regex.h>
size_t regerror(int errcode,  const regex_t *preg,
                char *errbuf, size_t errbuf_size);

regerror finds the description for the error code errcode for the regular expression preg. The description for errcode is assigned to errbuf. errbuf_size is a value that you provide that specifies the maximum message size that can be stored (the size of errbuf).

Regular expressions are described in detail under "Regular Expressions" in the VisualAge C++ Programming Guide.

The description strings for errcode are:

errcode

Description String

RE pattern not found

Invalid regular expression

Invalid collating element

Invalid character class

Last character is \

Invalid number in \digit

[] imbalance

 or () imbalance

\{ \} or { } imbalance

Invalid \{ \} range exp

Invalid range exp endpoint

Out of memory

?*+ not preceded by valid RE

Invalid multibyte character

^ anchor and not BOL

$ anchor and not EOL

regerror returns the size of the buffer needed to hold the string that describes the error condition.

This example compiles an invalid regular expression, and prints an error message using regerror.

#include <sys/types.h>#include <regex.h>
#include <stdio.h>
#include <stdlib.h>

int main(void)
{
   regex_t preg;
   char    *pattern = "a[missing.bracket";
   int     rc;
   char    buffer[100];

   if (0 != (rc = regcomp(&preg, pattern, REG_EXTENDED))) {
      regerror(rc, &preg, buffer, 100);
      printf("regcomp() failed with '%s'\n", buffer);
      exit(EXIT_FAILURE);
   }
   return 0;

   /****************************************************************************
      The output should be similar to :

      regcomp() failed with '[] imbalance'
   ****************************************************************************/
}

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