c++ - 如何在 boost regex_search 中获取原始字符串前缀

Question

我在 boost 中使用 regex_search，如下所示：

std::string symbol = "abcd1234";

boost::regex regExpr("(\\d{4})", boost::regex::icase);

boost::smatch regMatch;

boost::regex_search(symbol, regMatch, regExpr);

我需要得到的是：“abcd”，即到第一个匹配的reg 表达式的原始字符串。这怎么可能？提前致谢...

Answer 1

The following should work:

^(.*?)\\d{4}

Explanation:

^ - the start of the string
. - wild-card
.*? - zero or more (*) wild-cards (.), matched non-greedily (?), so you get the first match, not the last one

So you match everything from the start of the string to the digits.

Alternative using boost functionality:

regMatch.prefix() should return the required string.