GetString, exemple de méthode (VC++)

Cet exemple illustre la méthode GetString.

Supposons que vous déboguiez un problème d’accès aux données et que vous souhaitiez trouver un moyen simple et rapide d’imprimer le contenu actuel d’un petit Recordset.

Exemple

// BeginGetString.cpp  
// compile with: /EHsc /c  
#import "msado15.dll" no_namespace rename("EOF", "EndOfFile")  
  
#include <ole2.h>  
#include <stdio.h>  
#include <conio.h>  
#include <string.h>  
  
// Function declarations  
inline void TESTHR(HRESULT x) {if FAILED(x) _com_issue_error(x);};  
void GetStringX(void);  
void PrintProviderError(_ConnectionPtr pConnection);  
void PrintComError(_com_error &e);  
  
inline char* mygets(char* strDest, int n) {     
   char strExBuff[10];  
   char* pstrRet = fgets(strDest, n, stdin);  
  
   if (pstrRet == NULL)  
      return NULL;  
  
   // Exhaust the input buffer.  
   if (!strrchr(strDest, '\n'))  
      do {  
         fgets(strExBuff, sizeof(strExBuff), stdin);  
      } while (!strrchr(strExBuff, '\n'));  
   else  
      // Replace '\n' with '\0'  
      strDest[strrchr(strDest, '\n') - strDest] = '\0';  
  
   return pstrRet;  
}  
  
int main() {  
   if (FAILED(::CoInitialize(NULL)))  
      return -1;  
   GetStringX();  
   ::CoUninitialize();  
}  
  
void GetStringX() {  
   HRESULT  hr = S_OK;  
  char * token1;  
  
   // Define ADO object pointers.  
   // Initialize pointers on define.  
   // These are in the ADODB::  namespace.  
   _ConnectionPtr pConnection = NULL;  
   _RecordsetPtr pRstAuthors = NULL;  
  
   // Define string variables.  
   _bstr_t strCnn("Provider='sqloledb'; Data Source=My_Data_Source; Initial Catalog='pubs'; Integrated Security='SSPI';");  
   _bstr_t varOutput;   
   char *strPrompt = "Enter a state (CA, IN, KS, MD, MI, OR, TN, UT): ";  
   char strState[3], *pState;  
  
   try {  
      // Open connection.  
      TESTHR(pConnection.CreateInstance(__uuidof(Connection)));  
  
      // Open a command object for a stored procedure,   
      // with one parameter.  
      TESTHR(pRstAuthors.CreateInstance(__uuidof(Recordset)));  
  
      printf("%s",strPrompt);  
      mygets(strState, 3);  
  
      pState = strtok_s(strState," \t", &token1);  
  
      char strQry[100];  
      _snprintf_s(strQry, _countof(strQry), sizeof(strQry)-1, "SELECT au_fname, au_lname, address, city "  
         "FROM authors WHERE state = '%s'", pState);  
      strQry[sizeof(strQry)-1] = '\0';  
  
      pConnection->Open (strCnn, "", "", adConnectUnspecified);  
  
      pRstAuthors->Open(strQry, _variant_t((IDispatch*)pConnection, true),   
         adOpenStatic, adLockReadOnly, adCmdText);  
  
      if (pRstAuthors->RecordCount > 0)  {  
         // Use all defaults: get all rows, TAB column delimiter,   
         // CARRIAGE RETURN row delimiter, empty-string null delimiter  
         long lRecCount =  pRstAuthors->RecordCount;  
         _bstr_t varTab("\t");  
         _bstr_t varRet("\r");  
         _bstr_t varNull("");  
         varOutput = pRstAuthors->GetString(adClipString, lRecCount, varTab, varRet, varNull);  
         printf("State = '%s'\n", strState);  
         printf ("Name            Address            City\n");  
         printf ("%s\n", (LPCTSTR)varOutput);  
      }  
      else  
         printf("\nNo rows found for state = '%s'\n", pState);  
   }   
   catch(_com_error &e) {  
      // Notify the user of errors if any.  
      // Pass a connection pointer accessed from the Recordset.  
      PrintProviderError(pConnection);  
      PrintComError(e);  
   }  
  
   // Clean up objects before exit.  
   if (pRstAuthors)  
      if (pRstAuthors->State == adStateOpen)  
         pRstAuthors->Close();  
   if (pConnection)  
      if (pConnection->State == adStateOpen)  
         pConnection->Close();  
}  
  
void PrintProviderError(_ConnectionPtr pConnection) {  
   // Print Provider Errors from Connection object.  
   // pErr is a record object in the Connection's Error collection.  
   ErrorPtr pErr = NULL;  
  
   if( (pConnection->Errors->Count) > 0) {  
      long nCount = pConnection->Errors->Count;  
      // Collection ranges from 0 to nCount -1.  
      for (long i = 0 ; i < nCount ; i++) {  
         pErr = pConnection->Errors->GetItem(i);  
         printf("\t Error number: %x\t%s", pErr->Number, pErr->Description);  
      }  
   }  
}  
  
void PrintComError(_com_error &e) {  
   _bstr_t bstrSource(e.Source());  
   _bstr_t bstrDescription(e.Description());  
  
   // Print Com errors.  
   printf("Error\n");  
   printf("\tCode = %08lx\n", e.Error());  
   printf("\tCode meaning = %s\n", e.ErrorMessage());  
   printf("\tSource = %s\n", (LPCSTR) bstrSource);  
   printf("\tDescription = %s\n", (LPCSTR) bstrDescription);  
  
}  

Exemple d’entrée

MD  

Exemple de sortie

Enter a state (CA, IN, KS, MD, MI, OR, TN, UT): State = 'md'  
Name            Address            City  
Sylvia   Panteley   1956 Arlington Pl.   Rockville  

Voir aussi

GetString, méthode (ADO)
Recordset, objet (ADO)