Stackoverflow: How to convert from UTC to local time in C?<\/a>
\nI converted the code from C to C++ and make it shorter.<\/p>\n\r\n\/\/ replace non std function strptime with std::get_time\r\n\r\n#include <iostream>\r\n#include <sstream>\r\n#include <iomanip>\r\n#include <ctime>\r\n\r\n\/*\r\n Convert from a broken down date time structure from UTC to localtime.\r\n See https:\/\/stackoverflow.com\/questions\/9076494\/how-to-convert-from-utc-to-local-time-in-c\r\n*\/\r\nstd::tm UTC2localtime(std::tm tp) {\r\n \/\/ make sure Daylight saving time flag is not accidentally switched on in UTC time\r\n tp.tm_isdst = 0;\r\n\r\n \/\/ get seconds since EPOCH for this time\r\n const time_t utc = std::mktime(&tp);\r\n std::cout << "UTC date and time in seconds since EPOCH: " << utc << "\\n";\r\n\r\n \/\/ convert UTC date and time (Jan. 1, 1970) to local date and time\r\n std::tm e0{};\r\n e0.tm_mday = 1;\r\n e0.tm_year = 70;\r\n\r\n \/\/ get time_t EPOCH value for e0. This handles daylight saving stuff.\r\n \/\/ The value is e.g. -3600 for 1h difference between the timezones\r\n const time_t diff = std::mktime(&e0);\r\n\r\n \/\/ calculate local time in seconds since EPOCH\r\n const time_t local = utc - diff;\r\n std::cout << "local date and time in seconds since EPOCH: " << local << "\\n";\r\n\r\n \/\/ convert seconds since EPOCH for local time into local_tm time structure\r\n std::tm local_tm;\r\n if(localtime_r(&local, &local_tm) == nullptr) {\r\n throw std::system_error(errno, std::generic_category(), "UTC2localtime(): in conversion vom UTC to localtime");\r\n }\r\n return local_tm;\r\n}\r\n\r\nint main() {\r\n \/\/ hard coded date and time in UTC\r\n std::string datetime = "2013 11 30 23 30 26";\r\n std::cout << "UTC date and time to be converted in local time: " << datetime << "\\n";\r\n\r\n \/\/ put values of datetime into time structure\r\n std::tm UTC_tm{};\r\n std::istringstream ss(datetime);\r\n ss >> std::get_time(&UTC_tm, "%Y %m %d %H %M %S");\r\n\r\n if(ss.fail()) {\r\n throw std::runtime_error("Can not parse datetime from datetime '" + datetime + "' to format %Y %m %d %H %M %S");\r\n }\r\n\r\n const std::tm local_tm = UTC2localtime(UTC_tm);\r\n std::cout << "local date and time: " << std::put_time(&local_tm, "%Y-%m-%d %H:%M:%S %Z") << "\\n";\r\n}\r\n<\/pre>\n","protected":false},"excerpt":{"rendered":"Convert from a broken down date time structure from UTC to localtime in C++. See Stackoverflow: How to convert from UTC to local time in C? I converted the code from C to C++ and make it shorter. \/\/ replace non std function strptime with std::get_time #include <iostream> #include <sstream> #include <iomanip> #include <ctime> \/* […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[17],"class_list":["post-5153","post","type-post","status-publish","format-standard","hentry","category-allgemein","tag-cpp"],"_links":{"self":[{"href":"http:\/\/roboblog.fatal-fury.de\/index.php?rest_route=\/wp\/v2\/posts\/5153","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/roboblog.fatal-fury.de\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/roboblog.fatal-fury.de\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/roboblog.fatal-fury.de\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"http:\/\/roboblog.fatal-fury.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=5153"}],"version-history":[{"count":4,"href":"http:\/\/roboblog.fatal-fury.de\/index.php?rest_route=\/wp\/v2\/posts\/5153\/revisions"}],"predecessor-version":[{"id":5317,"href":"http:\/\/roboblog.fatal-fury.de\/index.php?rest_route=\/wp\/v2\/posts\/5153\/revisions\/5317"}],"wp:attachment":[{"href":"http:\/\/roboblog.fatal-fury.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=5153"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/roboblog.fatal-fury.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5153"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/roboblog.fatal-fury.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5153"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}