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jin

Fri Mar 02, 2007 1:01 am


Parameter Passing Help

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Hey i have a function that has parameters of an int and a pointer to an object. i am passing in an int and an address of an object. the function finds the object with the int value. i would like to change the address of the object being passed in to the to the one in the function. how would i go about doing this.

PS: cannot change parameters to references and cannot change return type.

if u dont understand that 

in main
Database.retrieve(x, &tempRecord)

the function
retrieve(unsigned int studentNum, studentRecord* searchRecord)
{
	for (int index = 0; index < _next_index; index++)
	{
		if (_arrayDB[index]->getStudentNumber() == studentNum)
		{
			searchRecord = _arrayDB[index];
		}
	}
}

i want tempRecord in main to have address of _arrayDB[index]

appreciate any help


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abcdefghijklmnopqrstuvwxy

Sun Mar 04, 2007 7:23 pm


RE:Parameter Passing Help

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retrieve(unsigned int studentNum, studentRecord* searchRecord //a pointer named searchRecord points to the address of tempRecord)
{
   for (int index = 0; index < _next_index // where is this declared?; index++)
   {
      if (_arrayDB[index]->getStudentNumber() == studentNum)
      {
         searchRecord = _arrayDB[index]; //now the pointer searchRecord points to the studentRecord* located at index.  We haven't changed tempRecord.
         break;
      }
   }
}


But what is tempRecord exactly?  It is an object you created on the stack.  Not a pointer.  When you pass it's address to this function you can manipulate that object, but you can't turn that object into a pointer by supplying its address.  

In order for tempRecord to have an address which can be changed you need to declare it as a pointer, not an object.  


studentRecord* tempRecord = new studentRecord;

//then pass it to the function like so: 

Database.retrieve(num, tempRecord);


But you mentioned you cannot change any parameters.  Well, without changing any parameters you CANNOT change the address of tempRecord to anything, because it is not a poitner.  But you could make the value of tempRecord equal the value of _arrayDB
*searchRecord = *_arrayDB[index];


If you don't know about overloading the = operator than google it or find the answer in these forums.  wtd covered it a few times I think in the tutorial section.