谁用过GNU C 的正则表达式

cgl520cn

这个函数
int regexec (regex_t *compiled, char *string, size_t nmatch, regmatch_t matchptr [], int
eflags)

eflags:
   REG_NOTBOL
（If this bit is set, then the beginning-of-line operator doesn't match the beginning of the
string (presumably
because it's not the beginning of a line).If not set, then the beginning-of-line operator
does match the beginning
of the string.）

   REG_NOTEOL

这两个植的含义是什么，这段英文看的不大明白