C++ 时间处理-从字符串中解析日期时间

1. 关键词
2. 问题
3. 解决思路
4. 代码实现
5. 测试代码
6. 运行结果
7. 源码地址

1. 关键词

C++ 时间处理从字符串中解析日期时间跨平台

2. 问题

C++如何将字符串的日期时间解析成对应的时间戳？

3. 解决思路

可以用正则表达式将字符串解析成 struct tm 类型的对象。
mktime()函数可以将 struct tm 类型的时间转换成时间戳。

4. 代码实现


#include <cstdint>
#include <string>
#include <vector>
#include <regex>
#include <time.h>using time_regex_type = std::pair<std::string, std::regex>;
using time_regex_vec_type = std::vector<time_regex_type>;std::string supported_time_formats(const time_regex_vec_type &fmtlist)
{std::string time_fmts;for (size_t i = 0; i < fmtlist.size(); i++){time_fmts += fmtlist[i].first + "\n";}return time_fmts;
}bool datetime::verify_time(const struct tm &time)
{// 校验年if (time.tm_year < 1900){CUTL_ERROR("the year should be >= 1900");return false;}// 校验月if (time.tm_mon < 1 || time.tm_mon > 12){CUTL_ERROR("the month should be between 1 and 12");return false;}// 校验日std::vector<int> large_month = {1, 3, 5, 7, 8, 10, 12};if (std::find(large_month.begin(), large_month.end(), time.tm_mon) != large_month.end() && (time.tm_mday < 1 || time.tm_mday > 31)){CUTL_ERROR("the day should be between 1 and 31 for " + std::to_string(time.tm_mon) + " month");return false;}std::vector<int> small_month = {4, 6, 9, 11};if (std::find(small_month.begin(), small_month.end(), time.tm_mon) != small_month.end() && (time.tm_mday < 1 || time.tm_mday > 30)){CUTL_ERROR("the day should be between 1 and 30 for " + std::to_string(time.tm_mon) + " month");return false;}if (time.tm_mon == 2){auto is_leap_year = [](int year){ return (year % 4 == 0 && year % 100 != 0) || (year % 400 == 0); };if (is_leap_year(time.tm_year) && (time.tm_mday < 1 || time.tm_mday > 29)){CUTL_ERROR("the day should be between 1 and 29 for " + std::to_string(time.tm_year) + "-" + fmt_uint(time.tm_mon, 2));return false;}if (!is_leap_year(time.tm_year) && (time.tm_mday < 1 || time.tm_mday > 28)){CUTL_ERROR("the day should be between 1 and 28 for " + std::to_string(time.tm_year) + "-" + fmt_uint(time.tm_mon, 2));return false;}}// 校验时分秒if (time.tm_hour < 0 || time.tm_hour > 23){CUTL_ERROR("the hour should be between 0 and 23");return false;}if (time.tm_min < 0 || time.tm_min > 59){CUTL_ERROR("the minute should be between 0 and 59");return false;}if (time.tm_sec < 0 || time.tm_sec > 59){CUTL_ERROR("the second should be between 0 and 59");return false;}return true;
}uint64_t parse_datetime(const std::string &time_text, int isdst)
{std::smatch matchRes;bool result = false;static time_regex_vec_type fmt_list = {// 0/1, 2/3, 4/5, 6/7的顺序不能反，因为不含毫秒数的时间会被优先匹配到std::make_pair("YYYY-MM-DD HH:MM:SS.sss", std::regex(R"((\d{4})-(\d{2})-(\d{2})[ ](\d{2}):(\d{2}):(\d{2}).(\d{3}))")),std::make_pair("YYYY-MM-DD HH:MM:SS", std::regex(R"((\d{4})-(\d{2})-(\d{2})[ ](\d{2}):(\d{2}):(\d{2}))")),std::make_pair("YYYY.MM.DD HH:MM:SS.sss", std::regex(R"((\d{4}).(\d{2}).(\d{2})[ ](\d{2}):(\d{2}):(\d{2}).(\d{3}))")),std::make_pair("YYYY.MM.DD HH:MM:SS", std::regex(R"((\d{4}).(\d{2}).(\d{2})[ ](\d{2}):(\d{2}):(\d{2}))")),std::make_pair("YYYY/MM/DD HH:MM:SS.sss", std::regex(R"((\d{4})/(\d{2})/(\d{2})[ ](\d{2}):(\d{2}):(\d{2}).(\d{3}))")),std::make_pair("YYYY/MM/DD HH:MM:SS", std::regex(R"((\d{4})/(\d{2})/(\d{2})[ ](\d{2}):(\d{2}):(\d{2}))")),std::make_pair("YYYYMMDD HH:MM:SS.sss", std::regex(R"((\d{4})(\d{2})(\d{2})[ ](\d{2}):(\d{2}):(\d{2}).(\d{3}))")),std::make_pair("YYYYMMDD HH:MM:SS", std::regex(R"((\d{4})(\d{2})(\d{2})[ ](\d{2}):(\d{2}):(\d{2}))")),};for (size_t i = 0; i < fmt_list.size(); i++){auto &fmt_text = fmt_list[i].first;auto &fmt_pattern = fmt_list[i].second;result = std::regex_search(time_text, matchRes, fmt_pattern);if (result){CUTL_DEBUG("matched regex: " + fmt_text);break;}}if (!result || matchRes.size() < 7){auto time_fmts = supported_time_formats(fmt_list);CUTL_ERROR("Only the following time formats are supported:\n" + time_fmts);return 0;}CUTL_DEBUG("matchRes size:" + std::to_string(matchRes.size()) + ", res:" + matchRes[0].str());// 解析毫秒值int ms = 0;if (matchRes.size() == 8){ms = std::stoi(matchRes[7].str());}// 解析tm结构的时间struct tm time = {};if (matchRes.size() >= 7){for (size_t i = 1; i < 7; i++){time.tm_year = std::stoi(matchRes[1]);time.tm_mon = std::stoi(matchRes[2]);time.tm_mday = std::stoi(matchRes[3]);time.tm_hour = std::stoi(matchRes[4]);time.tm_min = std::stoi(matchRes[5]);time.tm_sec = std::stoi(matchRes[6]);time.tm_isdst = isdst;}}if (!verify_time(time)){return 0;}// 转换为时间戳time.tm_year -= 1900;time.tm_mon -= 1;auto ret = mktime(&time);if (ret == -1){CUTL_ERROR("mktime() failed");return 0;}auto s = static_cast<uint64_t>(ret);return s;
}

5. 测试代码

#pragma once#include <iostream>
#include "timecount.h"
#include "common.hpp"void TestDatetimeParseString()
{// 字符串解析成时间PrintSubTitle("TestDatetimeParseString");auto dt0 = parse_datetime(" 2024-03-02 14:18:44 ");std::cout << "dt0: " << dt0 << std::endl;auto dt2 = parse_datetime(" 2024.03.12 14:18:44");std::cout << "dt2: " << dt2 << std::endl;
}

6. 运行结果

--------------------------------------TestDatetimeParseString---------------------------------------
dt0: 2024-03-02 14:18:44.000
dt2: 2024-03-12 14:18:44.000