C++ TR1 正则表达式 - 多行选项

Question

我以为 $ 表示字符串的结尾。然而，下面的一段代码给出了“testbbbccc”作为结果，这让我感到非常惊讶......这意味着 $ 实际上匹配行尾，而不是整个字符串的结尾。

#include <iostream>
#include <regex>

using namespace std;

int main()
{
    tr1::regex r("aaa([^]*?)(ogr|$)");
    string test("bbbaaatestbbbccc\nddd");
    vector<int> captures;
    captures.push_back(1);
    const std::tr1::sregex_token_iterator end;
    for (std::tr1::sregex_token_iterator iter(test.begin(), test.end(), r, captures); iter != end; )
    {
        string& t1 = iter->str();
        iter++;
        cout &lt;&lt; t1;
    }
} 

我一直试图找到一个“多线”开关(实际上可以在 PCRE 中轻松找到)，但没有成功......有人能指出我正确的方向吗？

问候，R.P.

Answer 1

由于为 tr1 选择了 Boost::Regex，请尝试以下操作:

来自 Boost::Regex

Anchors:

A '^' character shall match the start of a line when used as the first character of an expression, or the first character of a sub-expression.

A '$' character shall match the end of a line when used as the last character of an expression, or the last character of a sub-expression.

所以你观察到的行为是正确的。

发件人:Boost Regex还有:

\A Matches at the start of a buffer only (the same as \`).
\z Matches at the end of a buffer only (the same as \').
\Z Matches an optional sequence of newlines at the end of a buffer: equivalent to the regular expression \n*\z

希望对您有所帮助。