這個小程序重現了我項目中的錯誤。 time_t變量轉換爲struct_tm,然後轉換爲字符串,並序列化爲文件。稍後,該字符串將從該文件加載,並應該轉換回time_t。結果time_t與原始時間相差一小時(可能是由於夏令時)。我只能更改反序列化部分,因爲文件格式應該保持不變。序列化和反序列化time_t變量後的結果不正確
#include "stdafx.h" #include <iostream> #include <string> #include <time.h> using namespace std; string FormatDateTime(struct tm* time); void Test(); int _tmain(int argc, _TCHAR* argv[]) { Test(); return 0; } string FormatDateTime(struct tm* time) { static const char* months[] = { "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" }; char s[30]; const char* month; if (time->tm_mon >= 0 && time->tm_mon < 12) { month = months[time->tm_mon]; } else { month = "??"; } sprintf(s, "%d-%s-%02d %02d:%02d:%02d", time->tm_year + 1900, month, time->tm_mday, time->tm_hour, time->tm_min, time->tm_sec); return s; } void Test() { // time_t variable is initialized with current time time_t t = time(NULL); // time_t variable is converted to struct tm and then to string struct tm* ptm = localtime(&t); char buffer[100]; sprintf(buffer, "%d %d %d %d %d %d", ptm->tm_mday, ptm->tm_mon + 1, ptm->tm_year + 1900, ptm->tm_hour, ptm->tm_min, ptm->tm_sec); cout << buffer << endl; // string is OK // string is saved to the file // ********************************************************************************************* // later this string is restored from the file // **** I can change something only after this line **** // struct tm stm; memset(&stm, 0, sizeof(stm)); sscanf(buffer, "%d %d %d %d %d %d", &stm.tm_mday, &stm.tm_mon, &stm.tm_year, &stm.tm_hour, &stm.tm_min, &stm.tm_sec); stm.tm_mon -= 1; stm.tm_year -= 1900; string s = FormatDateTime(ptm); cout << s << endl; // OK // ********************************************************************************************* // Now I need to convert struct tm to time_t and keep it in the variable time_t t1 = mktime(&stm); // not the same time - 1 hour difference if (t1 == t) { cout << "t1 == t" << endl; } else { cout << "t1 != t !!!!!" << endl; } // time_t is printed - result is incorrect // Utilities::FormatDateTime struct tm* ptm1 = localtime(&t1); s = FormatDateTime(ptm1); cout << s << endl; }
當地時間是11.33。結果:
19 7 2012 11 33 17 2012-Jul-19 11:33:17 t1 != t !!!!! 2012-Jul-19 12:33:17
如何更改此程序的最後部分以獲得正確結果?
這是什麼:'如果(時間 - > tm_mon> = 0 &&時間> tm_mon tm_mon]; }' – SingerOfTheFall 2012-07-19 08:35:30
@SingerOfTheFall - 問題被編輯 – 2012-07-19 08:42:32
可以嗎?。 't繁殖,它完全適用於我:'19 7 2012 12 45 48 2012-Jul-19 12:45:48 t1 == t 2012-Jul-19 12:45:48' – SingerOfTheFall 2012-07-19 08:46:01