POSIX扩展正则表达式是否支持\ d元字符？

Question

我有一个威腾简单的C程序如下：

#include <stdio.h> 
#include <regex.h> 

int main(int argc, char* argv[]) 
{ 
    regex_t re; 
    char *pattern = "\\d{3}([a-zA-Z]+).(\\d{2}|N/A)\\s\\1"; // use \d, but wouldn't match 
    const char *target = "123Hello N/A Hello"; 

    regcomp(&re, pattern, REG_EXTENDED|REG_NOSUB); 

    int ret = regexec(&re, target, (size_t) 0, NULL, 0); 
    if(ret == REG_NOMATCH) { 
     printf("\n%s\n does not match \n%s\n", target, pattern); 
    } 

    pattern = "[0-9]{3}([a-zA-Z]+).([0-9]{2}|N/A)\\s\\1"; // changes to [0-9], now OK 

    regcomp(&re, pattern, REG_EXTENDED|REG_NOSUB); 

    ret = regexec(&re, target, (size_t) 0, NULL, 0); 
    if(ret == REG_NOMATCH) { 
     printf("\n%s\n does not match \n%s\n", target, pattern); 
    } 

    regfree(&re); 
    return 0; 
} 

我已经阅读Wikipedia标准的POSIX正则表达式，我还没有找到该POSIX立场是否suports的\ d元字符的任何证据。

或者我的代码有一个微妙的错误？

Answer 1

据this，POSIX正则表达式不支持\d简写（和他们也不支持\w或\s）。