HOWTO: Read and Change the System Date with API Functions

• Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b, 5.0, 5.0a on the following platforms: NT, Win95

SUMMARY

This article presents a step-by-step demonstration on programmatically calling Windows application program interface (API) functions from Visual FoxPro to read and set the system date. The code example shows how to obtain the date in a short date format. The system date can be set manually in the Date tab through the Regional Settings applet in the Windows Control Panel.

MORE INFORMATION

The values passed to the GetLocaleInfo API are obtained from the file Winnls.h that ships with Visual C. The Winnls.h contains constants and declarations used for National Language Support for Windows applications. Below are a few values from the Winnls.h file that may be useful in a Visual FoxPro for Windows application.

   Hexadecimal Value               Description
   -------------------------------------------------------
   0x00000014            * Local monetary symbol.         *
   0x00000015            * International monetary symbol. *
   0x00000016            * Monetary decimal separator.    *
   0x00000017            * Monetary thousand separator.   *
   0x0000001D            * Date separator.                *
   0x0000001E            * Time separator.                *
   0x0000001F            * Short date format string.      *
   0x00000020            * Long date format string.       *
   0x0000002A            * Long name for Monday.          *
   0x0000002B            * Long name for Tuesday.         *
   0x0000002C            * Long name for Wednesday.       *
   0x0000002D            * Long name for Thursday.        *
   0x0000002E            * Long name for Friday.          *
   0x0000002F            * Long name for Saturday.        *
   0x00000030            * Long name for Sunday.          *
   0x00000031            * Abbreviated name for Monday.   *
   0x00000032            * Abbreviated name for Tuesday.  *
   0x00000033            * Abbreviated name for Wednesday.*
   0x00000034            * Abbreviated name for Thursday. *
   0x00000035            * Abbreviated name for Friday.   *
   0x00000036            * Abbreviated name for Saturday. *
   0x00000037            * Abbreviated name for Sunday.   *

Windows stores two types of date formats, long and short. The program below demonstrates how to read and set the short date format. Create a program and add the following code:

   * Begin code to read system short date format *
   *
   * Setup declaration and parameters
   Declare INTEGER GetLocaleInfo in Win32API LONG Locale, ;
      LONG LCType, STRING @LpLCData, INTEGER cchData

   * GetSystemDefaultLCID retrieves the system default locale identifier
   Declare LONG GetSystemDefaultLCID in Win32API

   Declare SetLocaleInfo in Win32API LONG Locale, LONG LCType, ;
      STRING @LpLCData
   dwLCID = GetSystemDefaultLCID()

   Locale = 2048              && For English language.
   LpLCData = space(255)      && Address of buffer information.
   cchData = LEN(LpLCData)    && Size of buffer, LpLCData.

   nretval = 0                && Number returned from API call.
   cShortdate= ""             && Hold original short date format.

   * Get version, VFP 5 uses Hexadecimal & decimal, VFP 3 only uses decimal
   IF "3.00"$VERSION()
      LCType = 31    && Type of information. Decimal 31 for short date.
   ELSE
      LCType = 0x1f  && Type of information. Hex 1f for short date.
   ENDIF

   * Obtain short date format
   nretval = GetLocaleInfo(Locale, LCType, @LpLCData, cchData)
   If nretval = 0 Then
      =MessageBox ("Could not get information.")
   Else
      =MessageBox (LpLCData, 32, "Short Date Format")
      cShortdate = LpLCData   && Store original date format.
   EndIf

   * Variable for new short date format
   cNewshortdate = "MM/dd/yy" && Short date style copied from Control
   Panel.

   setdate = SetLocaleInfo(dwLCID, LCType, cNewshortdate)

   * Reread the system short date to see change
   nretval = GetLocaleInfo(Locale, LCType, @LpLCData, cchData)
   =MessageBox (LpLCData, 32, "Updated short Date Format")

   * Now reset date to previous format
   cNewshortdate = cShortdate

   setdate = SetLocaleInfo(dwLCID, LCType, cNewshortdate)

   * Verify date is in original format
   nretval = GetLocaleInfo(Locale, LCType, @LpLCData, cchData)
   =MessageBox (LpLCData, 32, "Original short Date Format")

   * End of code

REFERENCES

Visual C++ Help, version 5.0; search on: "GetLocaleInfo," "SetLocaleInfo"