C++ compile error: redefinition of 'class::class' - c++

Question

I have added the errors within comment lines of the code for the highlighted lines by the compiler.
header file:
#ifndef ADDRESS_H_EXISTS
#define ADDRESS_H_EXISTS
#include <iostream>
#include <string>
using namespace std;
class Address{
private:
string address1;
string address2;
string city;
string state;
string zipCode;
public:
Address(){} //note: 'Address::Address()' previously defined here|
Address(
const string &address1,
const string &address2,
const string &city,
const string &state,
const string &zipCode
){}
NOTE: #endif exists at the end of header file
source file:
#include <iostream>
#include <string>
#include "address.h"
using namespace std;
Address::Address(){} // error: redefinition of 'Address::Address()'
Address::Address( // error: redefinition of 'Address::Address(const string&,
// const string&, const string&, const string&, const string&)'|
const string &address1,
const string &address2,
const string &city,
const string &state,
const string &zipCode
):
address1(address1),
address2(address2),
city(city),
state(state),
zipCode(zipCode)
{
Address::address1 = address1_c;
Address::address2 = address2_c;
Address::city = city_c;
Address::state = state_c;
Address::zipCode = zip_c;
}
All of the most popular questions about this error concluded that header guards were needed, although, there are guards already included in this code.
I thought I was misunderstanding how to properly separate the initialization list between header and source files but when I commented that out it was still producing the same error.

Answer 1

What you're typically supposed to do is define the function prototypes in the header file, and the function definition in the source file. However, in your header file, you seem to have specified a definition of the function already using the empty {} brackets. Hence the compiler is complaining that you've redefined the function definition in the source file. If you remove those two {} empty blocks in the header file and replace them with a semicolon ;, it should solve this error.
Basically, it should look like this in your header:
Address();
Address(
const string &address1,
const string &address2,
const string &city,
const string &state,
const string &zipCode
);

Answer 2

You are getting redefinition errors ( which i think are linker errors, and not compile errors ) because Address::Address() and Address::Address(const string&, const string&, const string&, const string&, const string&) are already defined in the header file, and you define them again in the CPP file
To avoid that, you need to replace function definition by declarations in your header file, by replacing {} by ; in your header file, this way :
public:
Address(); //By replacing '{}' by ';', you change that function definition into a function DECLARATION
Address(
const string &address1,
const string &address2,
const string &city,
const string &state,
const string &zipCode
); // Same for here
At the exception of inline and template functions, function declaration goes in header file, and definitions goes into the CPP file