Question

我想捕获一个异常，它在我的代码中使用Try / Catch发生，如下所示：

try
{
//my code
}
catch(std::exception &e)
   {
       std::wcout <<"An exception occured"<<" "<<e.what();
   }

但是这样的结构在我的代码中没有捕获异常。我在这一行中收到了Visual Studio的一个例外：

retcode = bcp_init(hdbc1,"information1", NULL,NULL, DB_IN);

而不是我的try / catch。

在这里你可以看到我的整个代码：

#include <stdio.h>
#include <string.h>
#include <windows.h>
#include <sql.h>
#include <sqlext.h>
#include<tchar.h>
#include<iostream>
#include<sqlncli.h>
#include<exception>
using namespace std;

SQLHENV henv = SQL_NULL_HENV;
HDBC hdbc1 = SQL_NULL_HDBC, hdbc2 = SQL_NULL_HDBC;
SQLHSTMT hstmt2 = SQL_NULL_HSTMT;

void Cleanup() {
   if (hstmt2 != SQL_NULL_HSTMT)
      SQLFreeHandle(SQL_HANDLE_STMT, hstmt2);

   if (hdbc1 != SQL_NULL_HDBC) {
      SQLDisconnect(hdbc1);
      SQLFreeHandle(SQL_HANDLE_DBC, hdbc1);
   }

   if (hdbc2 != SQL_NULL_HDBC) {
      SQLDisconnect(hdbc2);
      SQLFreeHandle(SQL_HANDLE_DBC, hdbc2);
   }

   if (henv != SQL_NULL_HENV)
      SQLFreeHandle(SQL_HANDLE_ENV, henv);
}

int main() {
try
{
   RETCODE retcode;

   // BCP variables.
   char *terminator = "\0";

   // bcp_done takes a different format return code because it returns number of rows bulk copied
   // after the last bcp_batch call.
   DBINT cRowsDone = 0;

   // Set up separate return code for bcp_sendrow so it is not using the same retcode as SQLFetch.
   RETCODE SendRet;



   // Allocate the ODBC environment and save handle.
   retcode = SQLAllocHandle (SQL_HANDLE_ENV, NULL, &henv);
   if ( (retcode != SQL_SUCCESS_WITH_INFO) && (retcode != SQL_SUCCESS)) {
      printf("SQLAllocHandle(Env) Failed\n\n");
      Cleanup();
      return(9);
   }

   // Notify ODBC that this is an ODBC 3.0 app.
   retcode = SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, (SQLPOINTER) SQL_OV_ODBC3, SQL_IS_INTEGER);
   if ( (retcode != SQL_SUCCESS_WITH_INFO) && (retcode != SQL_SUCCESS)) {
      printf("SQLSetEnvAttr(ODBC version) Failed\n\n");
      Cleanup();
      return(9);    
   }

   // Allocate ODBC connection handle, set bulk copy mode, and connect.
   retcode = SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc1);
   if ( (retcode != SQL_SUCCESS_WITH_INFO) && (retcode != SQL_SUCCESS)) {
      printf("SQLAllocHandle(hdbc1) Failed\n\n");
      Cleanup();
      return(9);
   }

   retcode = SQLSetConnectAttr(hdbc1, SQL_COPT_SS_BCP, (void *)SQL_BCP_ON, SQL_IS_INTEGER);
   if ( (retcode != SQL_SUCCESS_WITH_INFO) && (retcode != SQL_SUCCESS)) {
      printf("SQLSetConnectAttr(hdbc1) Failed\n\n");
      Cleanup();
      return(9);
   }

   // sample uses Integrated Security, create the SQL Server DSN using Windows NT authentication
   SQLWCHAR dsn[30] = L"mssqltest"; //Name DNS
   SQLWCHAR user[10] = L"di_test";
   SQLWCHAR pass[10] = L"di_test";
 //  SQLWCHAR tb[20]=L"information1";

   retcode = SQLConnectW(hdbc1, (SQLWCHAR *)dsn, SQL_NTS, (SQLWCHAR *) user, SQL_NTS, (SQLWCHAR *) pass, SQL_NTS);
   if ( (retcode != SQL_SUCCESS) && (retcode != SQL_SUCCESS_WITH_INFO) ) {
      printf("SQLConnect() Failed\n\n");
      Cleanup();
      return(9);
   }
    //  TRYODBC(hdbc1, SQL_HANDLE_DBC, retcode);
   // Initialize the bulk copy.



   retcode = bcp_init(hdbc1,"information1", NULL,NULL, DB_IN);
  /* TRYODBC(hdbc1, SQL_HANDLE_DBC, retcode);*/
   if ( (retcode != SQL_SUCCESS) && (retcode != SQL_SUCCESS_WITH_INFO) ) {
      printf("bcp_init(hdbc1) Failed\n\n");
      Cleanup();
      return(9);
   }

   //Define our array
   DBINT custIDs[] ={1,2,3,4};

   // Bind the program variables for the bulk copy.
   if( bcp_bind(hdbc1, (BYTE *)&custIDs, 0, sizeof(DBINT), NULL,0, SQLINT4, 2)==FAIL)
   {
       retcode=-1;
   }
   if ( (retcode != SQL_SUCCESS) && (retcode != SQL_SUCCESS_WITH_INFO)  ) {
      printf("bcp_bind(hdbc1) Failed\n\n");
      Cleanup();
      return(9);
   }

   // Could normally use strlen to calculate the bcp_bind cbTerm parameter, but this terminator 
   // is a null byte (\0), which gives strlen a value of 0. Explicitly give cbTerm a value of 1.
   if( bcp_bind(hdbc1,(LPCBYTE) custIDs, 2, SQL_VARLEN_DATA, NULL,0, SQL_C_NUMERIC, 3)==FAIL)
   {
       retcode=-1;
   }
   if ( (retcode != SUCCEED) ) {
      printf("bcp_bind(hdbc1) Failed\n\n");
      Cleanup();
      return(9);
   }


   if ( (SendRet = bcp_sendrow(hdbc1) ) != SUCCEED ) {
         printf("bcp_sendrow(hdbc1) Failed\n\n");
         Cleanup();
         return(9);
      }

   cRowsDone = bcp_done(hdbc1);
   if ( (cRowsDone == -1) ) {
      printf("bcp_done(hdbc1) Failed\n\n");
      Cleanup();
      return(9);
   }



   printf("Number of rows bulk copied after last bcp_batch call = %d.\n", cRowsDone);

   // Cleanup.
   SQLFreeHandle(SQL_HANDLE_STMT, hstmt2);
   SQLDisconnect(hdbc1);
   SQLFreeHandle(SQL_HANDLE_DBC, hdbc1);
   SQLDisconnect(hdbc2);
   SQLFreeHandle(SQL_HANDLE_DBC, hdbc2);
   SQLFreeHandle(SQL_HANDLE_ENV, henv);
   }
   catch(std::exception &e)
   {
       std::wcout <<"An exception occured"<<" "<<e.what();
   }
 }

Answer 1

您没有看到C ++异常。这就是微软称之为SEH异常，实际上是一个程序崩溃。你可以捕获那些（在MSDN上搜索__try和__except），但一般来说这就像Java NullPointerException - 这是一个编程错误，没有错误处理会解决这个问题。

此外，如果设置为“中断所有异常”，Visual Studio将在发生异常时中断，该异常也将在try / catch中处理。如果您继续执行，它将转到相应的catch＆amp;被处理。如果发生这种情况，请关闭“中断所有异常”。无论如何，它会在未经处理的情况下停止。

Answer 2

C ++不是Java。没有通用基类异常这样的东西，所以std::exception只是标准库抛出的所有异常的基类。

如果您想捕获任何异常（而不是任何可能发生的奇怪错误），您可以使用catch(...)。

如SingerOfTheFall的评论所示，您可以使用C ++ 11 std::current_exception来检查异常对象。

Try-Catch不会捕获异常

2 个答案: