problem when iterating through vector

[ybkumar77]

Hi,
I am not sure how to categorize my problem

I have a class with char* as member variables. and I am using a get method to print the variable. Now I create a vector and in to it, I am pushing the objects of the class. but while trying to print/access these class variables it is printing garbage values. let me simplify my code.

class employee {
private:
     char* firstName;
     char* lastName;
public:
     char* getFirstName()  const{
        return firstName;
     }

     char* getLastName() const {
         return lastName;
     }
   void loadEmpNameFromDb();
   employee* fetchEmpRecord();
   static std::vector <employee*> empVector;
};

that's what I have in my header file.
in the source or .cpp file I have the following code

employee::employee()
{//ctor}
employee::~employee()
{//dtor}
void loadEmpNameFromDb() {
 char  local_fname[30];
 char* local_lname[30];
//next 3 lines of code should perform connecting to the Db and access the emp records.
  DbConnection *db = new DbConnection(im_db_user, im_db_name, application, im_db_server);

if (sqlStatement->SQLexec("exec IM_get_NE_list_for_SUPI") == SUCCEED) {
       if ((stat = sqlStatement->SQLget_result()) != SUCCEED) {
          stat = sqlStatement->SQLbind("Dist_name", &local_fname, 31);
          stat = sqlStatement->SQLbind("System_type", &local_lname, 31);

           while() //looping for end of the records 
            {

               employee* empObjPtr = new employee();

               empObjPtr->firstName = local_fname;
               empObjPtr->lastName = local_lname;
               empVector.push_back(empObjPtr);
   
               empObjPtr=NULL;
            }
      }
   }
}

void employee:: displayEmpRecord() {
std::vector<employee*>::iterator cacheObjIter;
for(cacheObjIter = empVector.begin(); cacheObjIter ! = empVector.end(); cacheObjIter++) {
   cout <<"first name =" <<(*cacheObjPtr)->getFirstName()<<endl;
   cout<<"lastname=" <<(*cacheObjPtr)->getLastName()<<endl;
}
   
int main()
{
  employee mycompanyemp;
  mycompanyemp.loadEmpNameFromDb();
  mycompanyemp.fetchEmpRecord() ;
}

I have put the code in a most simplified manner I could think of.
Now the problem I see is the output is a garbage values.
I see that I am able to iterate 5 times meaning there are 5 records in the db and everytime it is printing the last record values that are partially junk characters.

the expected out put is some what like this
firstname = john
lastname = smith
===========
firstname = jack
lastname = hammer
===========
firstname = jill
lastname = nelson
=========== etc.
but I get the following output :
firstname =
lastname= nelso00
===========
firstname =
lastname= nelso00
===========
firstname =
lastname= nelso00
===========

not sure of what went wrong. but I fiddled with this code for the whole day and yet couldn't resolve it. problem looks pretty simple. but still I am not able to fix it. please help me.

[Ancient Dragon]

empObjPtr->firstName = local_fname;
empObjPtr->lastName = local_lname;

You have to allocate memory for firstName and lastName then copy the strings into those two variables. Since this is c++ you should use std::string instead of char*. But if you have to use char* then this is how to do it:

empObjPtr->firstName = new char[strlen(local_fname)+1];
strcpy(empObjPtr->firstName, local_fname);

Then don't forget to delete that memory before the program ends.

[ybkumar77]

Hi,
Thanks for the suggestion. I have to use char* variables only. also the suggestion you have mentioned doesn't have any impact on this. still i get the garbage values. for your information, I am printing the values immediately after inserting into the vector.
At that time it works fine. but when I try to access them using the other function it will not work. wish me luck in resolving this problem.

Regards,
Bharath

[ybkumar77]

Hi,
as suggested I have tried using RWCString instead of char*. now the problem is resolved. I mean that I am able to print the values successfully. But I see another problem. i.e, in the destructor, it's core dumping.
I am deleting the memory allocated in the following way.

employee::~employee()
{
  if (firstName!=NULL)
     delete firstName;
 if (lastName!=NULL)
    delete lastName);
}

Am I doing anything wrong here ?

Thanks,
Bharath