error LNK2005: "bool __cdecl"

[xtinab]

I keep getting these errors:
Validation.obj : error LNK2005: "bool __cdecl dotDashRules(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (?dotDashRules@@YA_NABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z) already defined in main.obj

Validation.obj : error LNK2005: "bool __cdecl IsValid(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (?IsValid@@YA_NABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z) already defined in main.obj

I can't get rid of them. This program is an email validation program, btw.

main.cpp

// Homework 1

#include <iostream>
#include <fstream>
#include <string>
#include "Validation.cpp"

using namespace std;

bool IsValid(const string& emailAddress);

void main()
{
	//Input file to read emails from
	ifstream in("Email.txt");

	//Output file to write 0s and 1s to
	ofstream out("Result.txt");


	//0. While we are not at the end of file...
	while(!in.eof())
	{
		string emailAddress;
	//1. Read email from Email.txt, capturing an entire line;
		getline(in, emailAddress);

	//2. Validate it
		bool isValid = IsValid(emailAddress);

	//3. Write result to Result.txt
		out << isValid << endl;
	}
	in.close();
	out.close();


	system("pause");
}

Validation.cpp

#include <iostream>
#include <string>
#include <fstream>
#pragma once
#define MAX_EMAIL_SIZE 320
#define MAX_LOCALPART_SIZE 64
#define MAX_DOMAIN_SIZE 255
#define VALID_LOCALPART_CHARS "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890+-."
#define DOT '.'
#define AT '@'
#define DOT_DOT ".."
#define DOT_DASH ".-"
#define DASH_DOT "-."
#define WHITE_SPACE ' '

using namespace std;

//Email validation function
bool dotDashRules(const string& name)
{
	int checkLocal = name.find(DOT_DOT);
	if(checkLocal != string::npos)
		return false;
	checkLocal = name.find(DOT_DASH);
	if(checkLocal != string::npos)
		return false;
	checkLocal = name.find(DASH_DOT);
	if(checkLocal != string::npos)
		return false;
	checkLocal = name.find(DOT);
	if(checkLocal == 0 || checkLocal == name.length())
		return false;
	checkLocal = name.find(WHITE_SPACE);
	if(checkLocal != string::npos)
		return false;
}

bool IsValid(const string& emailAddress)
{
	//1. Check emailAddress size
	if(emailAddress.length() > MAX_EMAIL_SIZE)
		return false;

	//2. Find '@' symbol
	int atPosition = emailAddress.find(AT);
	if(atPosition == string::npos)
		return false;

	//3. Extract localPart and domain
	string localPart, domain, domainString;
	int dot, domainDot;
	localPart = emailAddress.substr(0, atPosition-1);
	dot = emailAddress.rfind(".");
	domainString = emailAddress.substr(atPosition+1, (dot-1));
	domainDot = domainString.rfind(".");
	if(domainDot == string::npos)
		domain = emailAddress.substr(domainDot+1, dot-1);
	else
		domain = emailAddress.substr(atPosition+1, (dot-1));

	//CHECK localPart
	//4. Check localPart size
	if(localPart.length() > MAX_LOCALPART_SIZE)
		return false;

	//5. Check for valid characters
	int check = localPart.find_first_not_of(VALID_LOCALPART_CHARS);
	if(check != string::npos)
		return false;

	//6. Check localPart for '.' and '-' rule
	dotDashRules(localPart);

	//CHECK domain
	//7. Check size of domain
	if(domain.length() > MAX_DOMAIN_SIZE)
		return false;

	//8. Find TLD; start at end and look for '.'
	int topLevDo = emailAddress.rfind(DOT);

	//9. Extract TLD
	string topLevelDomain = emailAddress.substr(topLevDo+1);

	//10. Validate TLD
	ifstream infile("TLD.txt");
	string listDomain = "nothing";
	while(!infile.eof() && listDomain != topLevelDomain)
			infile >> listDomain;
	infile.close();
	if(listDomain != topLevelDomain)
		return false;

	//11. Extract subdomain
	string subdomain = emailAddress.substr(atPosition+1, (topLevDo-1));

	//12. Check subdomain for valid characters
	int subdomainCheck = subdomain.find_first_not_of(VALID_LOCALPART_CHARS);
	if(subdomainCheck != string::npos)
		return false;

	//13. Check subdomain for '.' and '-' rule
	if(!dotDashRules(subdomain))
		return false;
}

[thines01]

Line 6 should include a.h file, not a .cpp file

[jaskij]

@thines01: considering how the compiler interpets it, it should work, but you are 100% correct that this way shouldn't be used.

IMO, just delete line 10.

[xtinab]

I have tried deleting line 10 and it still does not compile.

[xtinab]

Line 6 should include a.h file, not a .cpp file

Even when I do that it still won't compile.

[jaskij]

Might be something VS specific, compiled just fine with g++ even without deleting line 10 ;P
Oh well, -Wall shows some warning, but nothing much.

Also, include cstdlib - you don't provide the header for the system() function. And you don't need that system("pause") anyways, since you don't output anything to the standard output, only to files.

[thines01]

When you delete 10 or replace it with a .h file, you get a different list of errors, right?
What is the first error?