C 正则表达式不匹配

Question

我在 http://www.regexpal.com/ 测试了以下正则表达式

([A-Z]{1}[a-z]+)+([_]{1}([A-Z]{1}[a-z]+)+)+[.][a-z]+

成功匹配以下文件名:

Butter_Butter.jpg    
JavaPiebald_Java_Piebald.jpg       
LowWhitePied_Pied.jpg  
Piebald_Piebald.jpg  
SpinnerBlast_Spider_Pinstripe_Pastel.jpg
Caramel_Caramel.jpg  
LightningPied_Pied_Axanthic.jpg  
Pastel_Pastel.jpg      
Spider_Spider.jpg    
Spinner_Spider_Pinstripe.jpg

当我在以下 C 代码中实现正则表达式时，我没有收到任何匹配项:

#define COLLECTION_REGEX "([A-Z]{1}[a-z]+)+([_]{1}([A-Z]{1}[a-z]+)+)+[.][a-z]+"

int is_valid_filename(char *filename)
{
    regex_t regex;
    int i, match;
    char msgbuf[100];

    match = 1;
    i = regcomp(&regex, COLLECTION_REGEX, 0);

    if (i)
    {
            perror("Could not compile regex");
    }
    else
    {
            match = regexec(&regex, filename, 0, NULL, 0);

            if (!match)
            {
                    puts("Match");
            }
            else if (match == REG_NOMATCH)
            {
                    puts("No match");
            }
            else
            {
                    regerror(match, &regex, msgbuf, sizeof(msgbuf));
                    puts(msgbuf);
            }
    }

    regfree(&regex);

    return match;
}

后续执行:

./a.out 
No match
No match
No match
No match
No match
No match
No match
No match
No match
No match

正则表达式看起来正确，我不确定为什么会得到这些结果。

<小时/>

GDB 的输出:

Breakpoint 1, is_valid_filename (filename=0x609050 "Piebald_Piebald.jpg") at crp-web-builder.c:76
76                      match = regexec(&regex, filename, 0, NULL, 0);
(gdb) continue
Continuing.
No match

Breakpoint 1, is_valid_filename (filename=0x609460 "LightningPied_Pied_Axanthic.jpg") at crp-web-builder.c:76
76                      match = regexec(&regex, filename, 0, NULL, 0);
(gdb) continue
Continuing.
No match

Breakpoint 1, is_valid_filename (filename=0x609870 "SpinnerBlast_Spider_Pinstripe_Pastel.jpg") at crp-web-builder.c:76
76                      match = regexec(&regex, filename, 0, NULL, 0);
(gdb) continue
Continuing.
No match

Answer 1

感谢乔纳森·莱夫勒。该行:

i = regcomp(&regex, COLLECTION_REGEX, 0);

应该是:

i = regcomp(&regex, COLLECTION_REGEX, REG_EXTENDED);