Boost datetime posix_time的time_input_facet无法解析单数字日期

安全阿岳

2026-9-29

使用Boost datetime posix_time组件的time_input_facet时，存在无法解析单数字月份日期的问题。最初提交问题时未查询到该缺陷的相关记录，已采纳的回答指出该问题已在Boost官方date_time项目的issue 106中记录。

#include <boost/date_time/posix_time/posix_time.hpp>
#include <vector>

void date_from_string(const std::string& format, const std::string& date_str, boost::posix_time::ptime& date) {
    auto* facet = new boost::posix_time::time_input_facet;
    facet->format(format.c_str());
    std::stringstream ss(date_str);
    ss.imbue(std::locale(std::locale::classic(), facet));
    ss >> date;
    // delete facet; > "Your program has UB. delete facet; leads to double-free."
}

int main() {
    std::cout << "Boost Version: " << BOOST_VERSION << std::endl; // 107500
    // Boost Version: 107500

    for (auto& i : std::vector<std::pair<std::string,std::string>>{ 
            {"%a, %d %b %Y %H:%M:%S %ZP","Thu, 17 Oct 2021 15:00:00 GMT"},
// 2021-Oct-17 15:00:00 from str: Thu, 17 Oct 2021 15:00:00 GMT using: %a, %d %b %Y %H:%M:%S %ZP
            {"%a, %d %b %Y %H:%M:%S %ZP","Thu, 7 Oct 2021 15:00:00 GMT"},
// not-a-date-time from str: Thu, 7 Oct 2021 15:00:00 GMT using: %a, %d %b %Y %H:%M:%S %ZP
            {"%d", "7"},
            // not-a-date-time from str: 7 using: %d
            {"%d", "07"}
            // 1400-Jan-07 00:00:00 from str: 07 using: %d
        }) {
        boost::posix_time::ptime m_date;
        date_from_string(i.first, i.second,m_date); 
        std::cout << boost::posix_time::to_simple_string(m_date) << " from str: " << i.second << " using: " << i.first << std::endl;
    }
}