C / C++ / MFC

1-Jan-08 18:54

Hi all,

I'm working on a dialog base application, dealing with the time zone details.

In the dialog box there is a text box to enter the time offset. Then user click the display button, on the next text box display the timezone name. If the given time offset have more than one timezone name, very first timezone name should be display.

That's my question.

I'm going to use Windows API for this. So that I want to read the timezone list. How can I do that using API with GetTimeZoneInformation()

I appreciate your help all the time...
Eranga Smile | :)

CodingLover1-Jan-08 22:42

1-Jan-08 22:42

I this way is much prefer. I have a time offset and want to find the time zone name. That mean I have to read the registry. How can I do that. I'm confusing how to search whole registry of time zone in following path.

SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Time Zones

Under the 'Time Zones' I can see whole registered time zones. I want to get the required one. How can I do that. How can I search the whole Time Zones with given time offset.

I appreciate your help all the time...
Eranga Smile | :)

CodingLover2-Jan-08 0:05

2-Jan-08 0:05

One step more done. Read the registry as follows.

HKEY hKey;// Handle to the registry
DWORD dwType = REG_SZ;// Data type

char buf[255];// Data
DWORD dwBufSize = sizeof(buf);

// Sub handle to the registry
const char* subKey = "SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Time Zones\\Afghanistan Standard Time";

// Open the handler
if(RegOpenKey(HKEY_LOCAL_MACHINE, subKey, &hKey) == ERROR_SUCCESS)
{
    // Do the processing, find the name
    if(RegQueryValueEx(hKey, "Display", 0, &dwType, (BYTE*)buf, &dwBufSize) == ERROR_SUCCESS)
    {
        AfxMessageBox(buf);
    }
    else
    {
        AfxMessageBox("Error in reading values.", MB_OK);
    }
    // Close the handler
    RegCloseKey(hKey);
}
else
{
    AfxMessageBox("Error in reading registry.", MB_OK);
}

As you can see, this code gives the values related to the Afghanistan Standard Time. I want to iterate through the list of Time Zones.

In this way each time zone I can compare the user time offset with register values.

I appreciate your help all the time...
Eranga Smile | :)

David Crow2-Jan-08 2:52

David Crow

2-Jan-08 2:52

Eranga Thennakoon wrote:
I want to iterate through the list of Time Zones.

So why not use RegEnumValue()?

"Normal is getting dressed in clothes that you buy for work and driving through traffic in a car that you are still paying for, in order to get to the job you need to pay for the clothes and the car and the house you leave vacant all day so you can afford to live in it." - Ellen Goodman

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

CodingLover2-Jan-08 18:38

2-Jan-08 18:38

I do the enumerating as follows. How can I avoid the multiple findings. I mean, say there is more than one time zone for same time offset. In that case I want to display the very first time zone name. Used a break statement as follows. For some offsets it doesn't work.

for (i=0; i < cSubKeys; i++)
       {
           cbName = MAX_KEY_LENGTH;
           // Enumerate subkeys of Time Zones
           retCode = RegEnumKeyEx(hKey, i, achKey, &cbName, NULL, NULL, NULL, &ftLastWriteTime);

       // Make the new path for the registry
           char newPath[255];
           sprintf(newPath, "%s\\%s", path, achKey);
           printf("\n%s", newPath);

       // Work with the second handler
           if(RegOpenKey(HKEY_LOCAL_MACHINE, newPath, &hSubKey) == ERROR_SUCCESS)
           {
               if(RegQueryValueEx(hSubKey, "Display", 0, &dwType, (BYTE*)buf, &dwBufSize) == ERROR_SUCCESS)
               {
                   string strDisplay(buf);// Display name
                   string strSub = strDisplay.substr(4, 6);

               // String comparing
                   int result;
                   result = strcmp(strSub.c_str(), str.c_str());
                   if(result == 0)
                   {
                       printf("\n%s", strDisplay.c_str());// Time offset
                       break;
                   }

               }
               RegCloseKey(hSubKey);
           }
           else
           {
               printf("\nNo ");
           }
       }

I appreciate your help all the time...
Eranga Smile | :)

dan o3-Jan-08 5:59

3-Jan-08 5:59

you wrote: For some offsets it doesn't work

which registry keys does it not work ?

CodingLover3-Jan-08 14:23

3-Jan-08 14:23

for -09:00 it wont work. i'm expecting it for Alaskan Standard Time time zone. That is the second subkey of the Time Zones key of the registry. My code don't recognized it at all.

I appreciate your help all the time...
Eranga Smile | :)

dan o3-Jan-08 21:36

3-Jan-08 21:36

i will use something like this:

i will store all zones into m_pszTimeZones
and after that it is easy to get information you want

.h
CStringArray m_pszTimeZones;

.cpp
void <myclassname>::TestTM
{
HKEY hKey, Key;
DWORD dwType = REG_SZ;
int iRet = 0;
CString strName, strValue, strPath, strKey;

strPath = _T("SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Time Zones");

iRet = RegOpenKeyEx(HKEY_LOCAL_MACHINE, strPath, 0, KEY_READ, &hKey);

if (iRet != ERROR_SUCCESS)
return;

TCHAR achKey[MAX_PATH];
TCHAR achClass[MAX_PATH] = _T("");
DWORD cchClassName = MAX_PATH;
DWORD cSubKeys;
DWORD cbMaxSubKey;
DWORD cchMaxClass;
DWORD cValues;
DWORD cchMaxValue;
DWORD cbMaxValueData;
DWORD cbSecurityDescriptor;
FILETIME ftLastWriteTime;

DWORD i;
DWORD retCode;

TCHAR buffer[MAX_PATH];
DWORD dwSize = sizeof(buffer);

// Get the class name and the value count.
RegQueryInfoKey(hKey, // key handle
achClass, // buffer for class name
&cchClassName, // length of class string
NULL, // reserved
&cSubKeys, // number of subkeys
&cbMaxSubKey, // longest subkey size
&cchMaxClass, // longest class string
&cValues, // number of values for this key
&cchMaxValue, // longest value name
&cbMaxValueData, // longest value data
&cbSecurityDescriptor, // security descriptor
&ftLastWriteTime); // last write time

// Enumerate the child keys, until RegEnumKeyEx fails. Then
// get the name of each child key and copy it into the list box.

for (i = 0, retCode = ERROR_SUCCESS;retCode == ERROR_SUCCESS; i++)
{
ZeroMemory(&achKey, sizeof(achKey));
cbMaxSubKey = sizeof(achKey);
retCode = RegEnumKeyEx(hKey, i, achKey, &cbMaxSubKey, NULL, NULL, NULL, &ftLastWriteTime);
if (retCode == (DWORD)ERROR_SUCCESS)
{
strName.Format( _T("%s"), achKey);

strKey = strPath + "\\" + strName;
iRet = RegOpenKeyEx(HKEY_LOCAL_MACHINE, strKey, 0, KEY_READ, &Key);

if (iRet == ERROR_SUCCESS)
{
ZeroMemory(&buffer, sizeof(buffer));
dwSize = sizeof(buffer); //again
iRet = RegQueryValueEx(Key, _T("Display"), NULL, &dwType, (BYTE *)buffer, &dwSize);

if (iRet == ERROR_SUCCESS)
{
strValue.Format(_T("%s"), buffer);
m_pszTimeZones.Add( strValue );
}

RegCloseKey(Key);
}
}
}
RegCloseKey( hKey );
}

CodingLover3-Jan-08 21:47

3-Jan-08 21:47

Then do the comparing with user inputs?

I appreciate your help all the time...
Eranga Smile | :)

dan o3-Jan-08 22:06

3-Jan-08 22:06

yes...

like where strInput = "-09:00"

CString strTest;
int i;
for(i=0;i<=m_pszTimeZones.GetUpperBound();i++)
{
strTest = m_pszTimeZones.GetAt(i);
strTest = strTest.Mid(4,6);
if ( strTest == strInput)
break;
}

CodingLover3-Jan-08 22:10

3-Jan-08 22:10

Ok, thanks. I'll check it and let you know.

I appreciate your help all the time...
Eranga Smile | :)

CodingLover6-Jan-08 19:49

6-Jan-08 19:49

Hey dan o, your code works fine. Where I'm going wrong is the use of my buffer. I'm not sure what exactly happened, but the changing of the buffer size for different time zones gives an error.

Thanks buddy,

At the same time, I'm try to do another thing. Say I want to get both display name and standard zone name. How can I do that through the above your code.

I appreciate your help all the time...
Eranga Smile | :)

dan o6-Jan-08 22:28

6-Jan-08 22:28

ok, anyway
just closing this item now...

just make a new stringarray
CStringArray m_pszTimeZonesNames

if (iRet == ERROR_SUCCESS)
{
ZeroMemory(&buffer, sizeof(buffer));
dwSize = sizeof(buffer); //again
iRet = RegQueryValueEx(Key, _T("Std"), NULL, &dwType, (BYTE *)buffer, &dwSize);

if (iRet == ERROR_SUCCESS)
{
strValue.Format(_T("%s"), buffer);
m_pszTimeZonesNames.Add( strValue );
}

have a nice day

CodingLover6-Jan-08 22:39