Format
#include <regex.h>
size_t regerror(int errcode, const regex_t *preg,
char *errbuf, size_t errbuf_size);Language Level: XPG4
Threadsafe: Yes.
Locale Sensitive: The behavior of this function might be affected by the LC_CTYPE and LC_COLLATE categories of the current locale. This function is not available when LOCALETYPE(*CLD) is specified on the compilation command. For more information, see Understanding CCSIDs and Locales.
Description
The regerror() function finds the description for the error code errcode for the regular expression preg. The description for errcode is assigned to errbuf. The errbuf_size value specifies the maximum message size that can be stored (the size of errbuf). The description strings for errcode are:
| errcode | Description String |
|---|---|
| REG_NOMATCH | regexec() failed to find a match. |
| REG_BADPAT | Invalid regular expression. |
| REG_ECOLLATE | Invalid collating element referenced. |
| REG_ECTYPE | Invalid character class type referenced. |
| REG_EESCAPE | Last character in regular expression is a \. |
| REG_ESUBREG | Number in \digit invalid, or error. |
| REG_EBRACK | [] imbalance. |
| REG_EPAREN | \( \) or () imbalance. |
| REG_EBRACE | \{ \} imbalance. |
| REG_BADBR | Expression between \{ and \} is invalid. |
| REG_ERANGE | Invalid endpoint in range expression. |
| REG_ESPACE | Out of memory. |
| REG_BADRPT | ?, *, or + not preceded by valid regular expression. |
| REG_ECHAR | Invalid multibyte character. |
| REG_EBOL | ^ anchor not at beginning of regular expression. |
| REG_EEOL | $ anchor not at end of regular expression. |
| REG_ECOMP | Unknown error occurred during regcomp() call. |
| REG_EEXEC | Unknown error occurred during regexec() call. |
Return Value
The regerror() returns the size of the buffer needed to hold the string that describes the error condition. The value of errno may be set to ECONVERT (conversion error).
Example that uses regerror()
This example compiles an invalid regular expression, and prints an error message using the regerror() function.
#include <regex.htm>
#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.'
**********************************************************/
}Related Information