Check if a pointer exsists

[Munkey01]

I am currently working on a program that needs to create as many files as the user specifies and I was having a little problem with the naming of the file. I tried to use my count variable to assign a name but fstream will not accept it. So now I am trying to use a char pointer and the heap to hold names. I am more worried with getting the pointer and all to work before I start to worry about how I will assign a value to the where the pointer is pointing. My code so far-

#include <fstream>
#include <iostream>   //I know, I know, but VC++6 complains
using namespace std;

char CreateName(int num)
{
	if (!pName)
	{
		*pName = new char;
		*pName = num;
		return *pName;
	}
	else
	{
		delete pName;
		*pName = new char;
		*pName = num;
		return *pName;			
	}
}

int main()
{
	int amnt;
	cout << "How many files?: ";
                cin >> amnt;
	for(int i; i < amnt; i++)
	{
		ofstream newfile(CreateName(i));
		newfile.close();
	}
	return 0;
}

I am not even sure if char is an acceptable return value, I don't see why not though. But I have not been able to test this out on a compiler yet (I already know it would bring up errors).

How would I check to see if the pointer already exsisted so I know if I need to delete it or not before trying to create a new one? Or should I try something else for the naming?

[Magos]

What is pName???
If it is a char** it might work, if you allocate memory for an array of char* first, but that wouldn't be so dynamic. I'd make a linked list of names instead:

typedef struct _NODE
{
   char* Name
   struct _NODE* NextNode;
}NODE;

[Munkey01]

pName is the pointer to where I will be storing the name of the file...

[matheo917]

if pName is a pointer you can for instance do 2 things:

first, if pName has already been declared before somewhere in the code, you can do the following:

    if(pName == NULL)
          cout << "pName is not allocatted b/c it point to NULL ";

or perhpas inside of 'constructor' at the time of intended allocation you can do the following:

#include<assert.h>   // include at the top of the program


     assert(pName != NULL);    //   checks if pName has allocated
                               //   a value (address) in your case
                               //    on the heap...

keep in mind that assert() function tends to terminate the execution process...


hope that answers your question
...........................
matheo917

[Munkey01]

Well what exactly is a char**, a pointer to a pointer?

[Magos]

Originally posted by Munkey01
Well what exactly is a char**, a pointer to a pointer?

Yup!
And since an array and a pointer is basically the same thing, char** can also be an array of pointers or a pointer to an array (depending on how you allocate the memory).