Converting FILETIME to timestamp

I would like to convert my FILETIME structure to timestamp. Is there an easy way to do it?
(The FILETIME structure is a 64-bit value representing the number of 100-nanosecond intervals since January 1, 1601.)

Actually I want to compare it to the current time and see if 29 days have passed since the file was last modified/created/accessed.

FileTimeToSystemTime() ?

But how do I convert the system time to timestamp? (Timestamp means seconds from 1. january 1970, it's used in many places)

> and see if 29 days have passed since the file was last modified/created/accessed.
So why the need to rebase to seconds since 1/1/1970

Just work out how many 100nS there are in 29 days (that's easy) and use the timestamp you have.

How about using Julian dates?

Code:

#include <windows.h>
#include <stdio.h>

LONG CalcDays(int iYear, int iMonth, int iDay)
{
    LONG lReturnDays = iDay;
    int iTemp1 = (14 - iMonth) / 12;
    int iTemp2 = iYear + 4800 - iTemp1;
    int iTemp3 = iMonth + 12 * iTemp1 - 3;

    lReturnDays += (153 * iTemp3 + 2)/5;
    lReturnDays += 365 * iTemp2 + iTemp2 / 4 - 32083;
    return lReturnDays;
}

BOOL CalcFileAge(char * szFile)
{
    LONG lFileDays, lCurrentDays;
    FILETIME ftCreate, ftAccess, ftWrite, ftLocal;
    SYSTEMTIME stCreate, stNow;
    HANDLE hFile; 

    hFile = CreateFile(szFile,           
        GENERIC_READ,             
        FILE_SHARE_READ,           
        NULL,                     
        OPEN_EXISTING,             
        FILE_ATTRIBUTE_NORMAL,     
        NULL);                     
    if (hFile == INVALID_HANDLE_VALUE) 
        return FALSE;   
    if (!GetFileTime(hFile, &ftCreate, &ftAccess, &ftWrite))
    {
        CloseHandle(hFile);
        return FALSE;
    }
    if (!FileTimeToLocalFileTime(&ftWrite, &ftLocal))
    {
        CloseHandle(hFile);
        return FALSE;
    }
    GetSystemTime(&stNow);
    FileTimeToSystemTime(&ftLocal, &stCreate);
    CloseHandle(hFile);
    lFileDays = CalcDays(stCreate.wYear,stCreate.wMonth,stCreate.wDay);
    lCurrentDays = CalcDays(stNow.wYear,stNow.wMonth,stNow.wDay);
    printf("%s is %ld day(s) old\n", szFile, (lCurrentDays - lFileDays));
    return TRUE;
}

int main(int argc, char **argv)
{
    CalcFileAge(argv[1]);
    return 0;
}

I already did it as Salem said...