关于c ++：序列化和反序列化time_t变量后的结果不正确

Incorrect result after serializing and deserializing time_t variable

这个小程序在我的项目中复制了这个错误。时间变量转换为struct_tm，然后转换为string，并序列化为文件。稍后，该字符串将从文件中加载，并应转换回时间。结果时间与原始时间相差一小时(可能是因为夏令时)。我只能更改反序列化部分，因为文件格式应该保持不变。

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#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;
}

当地时间是11点33分。结果：

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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后一部分以获得正确的结果？