std::regex_search

#include <cstddef>
#include <iostream>
#include <regex>
#include <string>
 
int main()
{
    std::string lines[] = {"Roses are #ff0000",
                           "violets are #0000ff",
                           "all of my base are belong to you"};
 
    std::regex color_regex("#([a-f0-9]{2})"
                            "([a-f0-9]{2})"
                            "([a-f0-9]{2})");
 
    // 简单匹配
    for (const auto& line : lines)
        std::cout << line << "：" << std::boolalpha
                  << std::regex_search(line, color_regex) << '\n';
    std::cout << '\n';
 
    // 展示每个匹配中有标记子表达式的内容
    std::smatch color_match;
    for (const auto& line : lines)
        if (std::regex_search(line, color_match, color_regex))
        {
            std::cout << "'" << line << "' 的匹配\n";
            std::cout << "前缀：'" << color_match.prefix() << "'\n";
            for (std::size_t i = 0; i < color_match.size(); ++i) 
                std::cout << i << "：" << color_match[i] << '\n';
            std::cout << "后缀：'" << color_match.suffix() << "\'\n\n";
        }
 
    // 重复搜索（参阅 std::regex_iterator）
    std::string log(R"(
        Speed:	366
        Mass:	35
        Speed:	378
        Mass:	32
        Speed:	400
	Mass:	30)");
    std::regex r(R"(Speed:\t\d*)");
    for (std::smatch sm; regex_search(log, sm, r);)
    {
        std::cout << sm.str() << '\n';
        log = sm.suffix();
    }
 
    // C 风格字符串演示
    std::cmatch cm;
    if (std::regex_search("this is a test", cm, std::regex("test"))) 
        std::cout << "\n在位置 " << cm.prefix().length()
                  << " 找到 " << cm[0] << '\n';
}