Converting C to C++

[buckwheat88]

Hi, I have to convert some of my programs from C to C++. I think I'm doing it right, but I'm getting errors. This is my original program:

/* million.c by Aron 10/03/2005 */

/* This program asks the user to input a dollar
 * amount and an interest rate, and the program 
 * will calculate how long it will take to reach
 * $1 million.  Input comes from the keyboard and
 * output is sent to the screen
 */

#include<stdio.h>
int main()
{
	/* Declaration */
	int years;
	double amount, rate;

	/* Heading */
	printf("Million\n\n");

	/* Input Section */
	do
   {
	printf("Enter Amount ");
	scanf("%lf", &amount);
   }
  while(amount < 1.00 || amount > 250000.0);

  do
   {
  printf("\nEnter Rate (Ex: .03, .04) ");
	scanf("%lf", &rate);
   }
  while(rate < .01 || rate > .29);

	/*Processing */
	years = 0;

	while(amount < 1000000.0)
	{
		++years;
		amount = amount + amount * rate; 
	}

	/* Output Section */
	printf("\n\n%d Years required to reach $%.02lf\n",
		years, amount);

	return 0;
}

and this is what I have so far in my converted program:

// million.cpp by Aron 11/27/2005

// This program asks the user to input a dollar
// amount and an interest rate, and the program 
// will calculate how long it will take to reach
// $1 million.  Input comes from the keyboard and
// output is sent to the screen

#include<stdio.h>
#include<iostream.h>
int main()
{
	// Declaration 
	int years;
	double amount, rate;

	// Heading
	cout <<"Million\n\n";

	// Input Section
	do
   {
	cout <<"Enter Amount ";
	cin >>"%lf", &amount;
   }
  while(amount < 1.00 || amount > 250000.0);

  do
   {
  cout <<"\nEnter Rate (Ex: .03, .04) ";
	cin >>"%lf", &rate;
   }
  while(rate < .01 || rate > .29);

	// Processing
	years = 0;

	while(amount < 1000000.0)
	{
		++years;
		amount = amount + amount * rate; 
	}

	// Output Section
	cout <<"\n\n%d Years required to reach $%.02lf\n",
		years, amount;

	return 0;
}

I'm getting the errors "local variable 'amount' used without having been initialized" and "local variable 'rate' used without having been initialized", but weren't they both initialized in the declaration?
Thanks in advance for the help

[Quantum1024]

No they weren't initialized they contrain random values, set them to 0 to avoid getting this message.
also use these includes

#include <iostream>
#include <fstream>

and use this

using namespace std;

[Tonto]

cin >> syntax is somewhat different than scanf. Readings:

Basic C++ I/O http://www.cplusplus.com/doc/tutorial/basic_io.html
Reference istream::operator>> http://www.cplusplus.com/ref/iostrea...ratorgtgt.html
C++ I/O FAQ http://www.parashift.com/c++-faq-lite/input-output.html

[jlf029]

// million.cpp by Aron 11/27/2005
// This program asks the user to input a dollar
// amount and an interest rate, and the program
// will calculate how long it will take to reach
// $1 million.  Input comes from the keyboard and
// output is sent to the screen
#include<iostream>
using namespace std;
int main()
{
	// Declaration
	int years;
	double amount, rate;
	// Heading
	cout <<"Million\n\n";
	// Input Section
	do {
		cout <<"Enter Amount ";
		cin >> amount;
	} while(amount < 1.00 || amount > 250000.0);
	do {
		cout <<"\nEnter Rate (Ex: .03, .04) ";
		cin >> rate;
	} while(rate < .01 || rate > .29);
	// Processing
	years = 0;
	while(amount < 1000000.0) {
		++years;
		amount = amount + amount * rate;
	}
	// Output Section
	cout <<"\n\n" << years << " Years required to reach $" << amount << endl;
	return 0;
}

I prefer c++ inputs using cin however scanf is easier to get required data from input line