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// Copyright 2016 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include <ctime>
#include <iostream>
#include <string>
std::string format(const std::string& fmt, const std::tm& tm) {
char buf[100];
std::strftime(buf, sizeof(buf), fmt.c_str(), &tm);
return buf;
}
int GetOffset(std::time_t, const std::string& zone) {
if (zone == "America/New_York") return -4 * 60 * 60;
return 0;
}
int main() {
const std::time_t now = std::time(nullptr);
// Shift epoch: UTC to "local time_t"
int off = GetOffset(now, "America/New_York");
const std::time_t now_nyc = now + off;
std::tm tm_nyc;
#if defined(_WIN32) || defined(_WIN64)
gmtime_s(&tm_nyc, &now_nyc);
#else
gmtime_r(&now_nyc, &tm_nyc);
#endif
std::cout << format("NYC: %Y-%m-%d %H:%M:%S\n", tm_nyc);
// Shift back: "local time_t" to UTC
off = GetOffset(now_nyc, "America/New_York");
const std::time_t now_utc = now_nyc - off;
return now_utc == now ? 0 : 1;
}
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