regcmp pattern $ 0含義

Question

我試圖瞭解regcmp()和regex()是如何工作的。我的代碼是

int main() 
{ 
    char *newcursor, *name; char *string; char ret0[9]; 

    name = regcmp("([A-Za-z][A-za-z0-9]{0,4})$0", (char *)0); 
    printf("name %s\n",&(*name)); 
    newcursor = regex(name, "filter:attrsonly:attrs", ret0); 
    printf("newcursor %s and ret0 %s\n",newcursor,ret0); 
    return 0; 
} 

在這裏，在第12行有哪些呢$0在模式([A-Za-z][A-za-z0-9]{0,4})$0的到底意味着什麼？

我在LINUX與regexec()和regcomp()功能替換regex()和regcmp()到端口的代碼從UNIX到Linux作爲regcmp()和regex()不存在在LINUX。

如果我從模式中刪除$0，它只會在LINUX執行regcomp()時給出預期的結果。 $0是什麼意思？

Answer 1

請允許我引用man 7 regex：

 '$' (matching the null string at the end of a line), 

機會使用基本正則表達式的UNIX程序爲：

Obsolete ("basic") regular expressions differ in several respects. 
    [ ... ] 
    '$' is an ordinary character except at the end of the RE or(!) 
    the end of a parenthesized subexpression 
    [ ... ] 

編輯：好吧，我應該已經看過了UNIX的regcmp過，我想你已經這樣做了：

(...)$n   The value of the enclosed regular expression is to be 
        returned. The value will be stored in the (n+1)th 
        argument following the subject argument. At most, ten 
        enclosed regular expressions are allowed. The regex() 
        function makes its assignments unconditionally. 

so this in this如果$0只是指定比賽結果應該在哪裏，那麼您可以將其忽略。