检验输入的mac是否是符合mac形式

unsigned int isvalidmac(char *value) {
int r = -1;           //0:valid, other:not valid
int cflag = 0;
const size_t nmatch = 10;
regmatch_t pm[10];
regex_t reg;
char *pattern = "^[0-9a-fA-F]\\([0-9a-fA-F]\\:[0-9a-fA-F]\\)\\{5\\4}{0-9a-fA-F}$"; //正则表达式

r = regcomp(®, pattern, cflags);
if (r == 0) {
r = regexec(®, value, nmatch, pm, cflags);
}
regfree(®);

return r;
}