C / C++ / MFC

void insertNode( string newName )
{	
    node *p, *n, *t;
 
    p = new node;
    p->data = newName;
    p->next = NULL;
 
    // iterate through the list, finding the right insertion spot
    n = first;
    t = first;
    while (NULL != n && p->data > n->data)
    {
        t = n;
        n = n->next;
    }
 
    // re-adjust the pointers

    if (NULL == first)
        // we inserted into an empty list
        first = p;
    else if (n == first)
    {
        // we inserted a new 'first' node
        first = p;
        p->next = n;
    }
    else
    {
        // we inserted an item someplace else, including the end
        t->next = p;
        p->next = n;
    }
}

BOOL OnPrompt();

int main(void)
{
	//Question:Will it be the best practice to do this: float c=0?
	//Question:I used float, but I am not sure if in this case better to use int or double?
 
	cout<<"Please select the task to perform:"<<endl;
	cout<<"Convert Fahrenheit to Centigrade (1)"<< endl;
	cout<<"Convert Centigrade to Fahrenheit(2)"<< endl;
	cout<<"Exit the program(3)"<< endl;
 	
	while(true)
	{
		if(OnPrompt())
			break;
	}
 
	return 0;
}
 
BOOL OnPrompt()
{
	int choice;
	float c; //Declare variable to be displayed.
	float f;

	cout<<"Please enter 1 or 2 (3 to exit program):";
	cin>>choice;
	switch (choice)
	{
		// use switch in order to do validation and calculation
		case 1:
		{
			cout<<"Enter value 
			in Fahrenheit:" ;
			cin>>f;
			c=((f-32)*5/9);
			cout<<"The value 
			in Centigrade is:"<<c<<endl;
			return TRUE;
			break;
		}
		case 2:
		{
			cout<<"Enter value in Centigrade:";
			cin>>c;
			f=((c+32)*9/5);
			cout<<"The value in Fahrenheit is:"<<f<<endl;
			return TRUE;
			break;
		}
		case 3:
		{
			cout<<"Thank you for using this program."<<endl;
			// If user enter 3 quit program
			// use return statement
			//Question:Is it any other way to quit the program other then use return?
			return TRUE;
			break;
		}
		default:
		{
			cout<<"Incorrect input"<< endl;
			return FALSE;
			// Default case used if user input the value outside the appropriate range
		}
	}
}

do
// use do-while loop
{