OTL 4.0, Example 648

(otl_exception, derived from a base class)

This example demonstrates how to derive otl_exception from a base class, which may be part of already existing exception class hierarchy.

Source Code

#include <iostream>
using namespace std;
#include <stdio.h>

const int BASE_EXCEPTION=1; // "Base exception" class Id.
const int DB_BASE_EXCEPTION=2; // "DB Base exception" class Id.

// Let's assume that the following class is the base of 
// the system exception class hierarchy
class my_base_exception{
public:

  my_base_exception(){}
  virtual ~my_base_exception(){}

  virtual int getType(void) const
  {
    return BASE_EXCEPTION;
  }

  virtual int getErrorCode(void) const
  {
    return 0;
  }

  virtual char* getErrorMessage(void) const
  {
    return "";
  }

};

// Compile OTL 4.0/ODBC in Windows. Informix CLI uses the
// regular ODBC header files in Windows
#define OTL_ODBC

// Uncomment the #defines below in Linux / Unix
//#define OTL_ODBC_UNIX
//#define OTL_INFORMIX_CLI
#define OTL_EXCEPTION_DERIVED_FROM my_base_exception

// This #define defines a set of new members in the otl_exception
// class
#define OTL_EXCEPTION_HAS_MEMBERS               \
  virtual int getType(void) const               \
  {                                             \
    return DB_BASE_EXCEPTION;                   \
  }                                             \
                                                \
  virtual int getErrorCode(void) const          \
  {                                             \
    return this->code;                          \
  }                                             \
                                                \
  virtual char* getErrorMessage(void) const     \
  {                                             \
    return (char*)this->msg;                    \
  }

#include <otlv4.h> // include the OTL 4.0 header file

otl_connect db; // connect object

void insert()
// insert rows into table

 otl_stream o(50, // buffer size
              "insert into test_tab values(:f1<float>,:f2<char[31]>)", 
                 // SQL statement
              db // connect object
             );
 char tmp[32];

 for(int i=1;i<=100;++i){
  sprintf(tmp,"Name%d",i);
  o<<(float)i<<tmp;
 }
}

void select()

 otl_stream i(50, // buffer size
              "select * from test_tab where f1>=:f11<int> and f1<=:f12<int>*2",
                 // SELECT statement
              db // connect object
             ); 
   // create select stream
 
 float f1;
 char f2[31];

 i<<8<<8; // assigning :f11 = 8, :f12 = 8
   // SELECT automatically executes when all input variables are
   // assigned. First portion of output rows is fetched to the buffer

 while(!i.eof()){ // while not end-of-data
  i>>f2>>f1; // a typo: f2 instead of f1
  cout<<"f1="<<f1<<", f2="<<f2<<endl;
 }

 i<<4<<4; // assigning :f11 = 4, :f12 = 4
   // SELECT automatically executes when all input variables are
   // assigned. First portion of output rows is fetched to the buffer

 while(!i.eof()){ // while not end-of-data
  i>>f1>>f2;
  cout<<"f1="<<f1<<", f2="<<f2<<endl;
 }

}

int main()
{
 otl_connect::otl_initialize(); // initialize Informix CLI environment
 try{

  db.rlogon("informix/tigger@informixsql"); // connect to Informix

  otl_cursor::direct_exec
   (
    db,
    "drop table test_tab",
    otl_exception::disabled // disable OTL exceptions
   ); // drop table

  otl_cursor::direct_exec
   (
    db,
    "create table test_tab(f1 int, f2 varchar(30))"
    );  // create table

  insert(); // insert records into table
  select(); // select records from table

 }
 catch(my_base_exception& ex){ // intercept the base exception
   if(ex.getType()==DB_BASE_EXCEPTION){ 
     // "database exception" is recognized
     // here, the otl_exception can be analyzed, or simply printed out
     cerr<<"Database exception:"<<endl;
     cerr<<"Code: "<<ex.getErrorCode()<<endl; // print out error code
     cerr<<"Message: "<<ex.getErrorMessage()<<endl; // print out the error message
   }else{
     // otherwise, do something else
     cerr<<"Base exception was caught..."<<endl;
   }
 }

 db.logoff(); // disconnect from Informix

 return 0;

}

Output

Database exception:
Code: 32000
Message: Incompatible data types in stream operation

Examples ContentsGo Home

Copyright © 1996-2023, Sergei Kuchin, email: skuchin@gmail.com, skuchin@gmail.com/a>.

Permission to use, copy, modify and redistribute this document for any purpose is hereby granted without fee, provided that the above copyright notice appear in all copies. THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.