I can't find two errors.

[HatchetMan302]

My program looks like it should run perfectly fine, however there are two linker errors that I cannot figure out. The first is that there is one unresolved external, the second is that main is referenced in function. If you guys could figure out where these errors are coming from, that would be great.

#include <iostream>
#include <iomanip>
#include <cmath>
using std::cout;
using std::cin;
using std::endl;
using std::setw;

int GetData();
void DisplayMenu(int & menuChoice);
void ProcessMenuChoice(int menuChoice, int & userNumber);
void IsPosNeg(int userNumber);
void IsOddEven(int userNumber);
double FindSqrt(int userNumber);
int FindNumDigits(int userNumber);
int FindDigitAtPosition(int userNumber, int specificDigit);
void DisplayAdditionTable();
void DisplayMultiplicationTable();

int main()
{
	int menuChoice = 0;
	int userNumber = 0;
	char userChoice = '\0';


	cout << "\t\t###NUMBER MANIPULATOR PROGRAM###\n" << endl;

	do
	{
		userNumber = GetData();

		DisplayMenu(menuChoice);

		ProcessMenuChoice(menuChoice, userNumber);

		cout << "Would you like to enter another number? (y/n): ";
		cin >> userChoice;

		cout << '\n' << endl;

	} while (userChoice == 'y' || userChoice == 'Y');

	cout << "\t\t###END OF PROGRAM###\n" << endl;

	return 0;
}

int GetData()
{
	int userNumber = 0;

	cout << "Please enter a number: ";
	cin >> userNumber

	while (userNumber < -1000000 || userNumber > 1000000)
	{
		cout << "\n\nYour value is too big or too small, please try again. ";
		cin >> userNumber;
	}

	return userNumber;
}

void DisplayMenu(int & menuChoice)
{
	cout << "\n\n1) Is the number odd or even?\n"
		<< "2) Is the number positive or negative?\n"
		<< "3) What is the square root of the number?\n"
		<< "4) How many digits are in the number?\n"
		<< "5) Display a certain digit in the number.\n"
		<< "6) Display an addition table for the numbers 1 to 12\n"
		<< "7) Display a multiplication table for the numbers 1 to 12\n"
		<< endl;

	cout << "Enter a menu choice: ";
	cin >> menuChoice;

	while (menuChoice < 1 || menuChoice > 7)
	{
		cout << "\n\nInvalid entry, please try again. ";
		cin >> menuChoice;
	}

	cout << '\n' << endl;
}

void ProcessMenuChoice(int menuChoice, int & userNumber)
{
	double sqrtNumber = 0;
	int numberOfDigits = 0;
	int specificDigit = 0;

	switch (menuChoice)
	{
	case 1:
		IsOddEven(userNumber);
		break;

	case 2:
		IsPosNeg(userNumber);
		break;

	case 3:
		sqrtNumber = FindSqrt(userNumber);

		cout << "The square root of you number is " 
			<< sqrtNumber << '\n' << endl;
		break;

	case 4:
		numberOfDigits = FindNumDigits(userNumber);

		cout << "The number of digits in your number is " 
			<< numberOfDigits << '\n' << endl;
		break;

	case 5:
		specificDigit = FindDigitAtPosition(userNumber, specificDigit);

		cout << "The digit you wanted is " << specificDigit << '\n' << endl;
		break;

	case 6:
		DisplayAdditionTable();
		break;

	case 7:
		DisplayMultiplicationTable();
	}

	cout << '\n' << endl;
}

void IsOddEven(int userNumber)
{
	int remainder = userNumber / 2;

	if (userNumber == 0)
		cout << "\n\nYour number is zero.\n" << endl;
	else if (remainder == 0)
		cout << "\n\nour number is Even.\n" << endl;
	else
		cout << "\n\nYour number is Odd.\n" << endl;
}

void IsPosNeg(int userNumber)
{
	if (userNumber > 0)
		cout << "\n\nYour number is Positive.\n" << endl;
	else if (userNumber < 0)
		cout << "\n\nYour number is Negative.\n" << endl;
	else
		cout << "\n\nYour number is Zero.\n" << endl;
}

double FindSqrt(int userNumber)
{
	double sqrtNumber = 0;

	sqrt_number = sqrt(userNumber);

	cout << "\n\nThe square root of your number is " << sqrt_number << '\n' << endl;

	return sqrtNumber;
}

int FindNumDigits(int userNumber)
{
	for (int digit = 1; userNumber > 0; digit++)
	{
		userNumber /= 10;
		numberOfDigits = digit;
	}

	return numberOfDigits;
}

int FindDigitAtPosition(int userNumber, int specificDigit)
{
	int userDigit = 0;

	cout << "\n\nWhich digit position do you want? ";
	cin >> userDigit;

	for (int a = 1; a <= userDigit; a++)
	{
		specificDigit = userNumber % 10;
		userNumber /= 10;
	}

	return specificDigit;
}

void DisplayAdditionTable()
{
	int topRow = 0;
	int topLine = 0;
	int rowVar = 0;
	int displayRow = 0;

	cout << setw(5) << " ";

	while (topRow <= 12)
	{
		cout << setw(2) << topRow << " ";
		topRow++;
	}

	cout << endl;
	cout << "------";

	while (topLine <= 12)
	{
		cout << "---";
		topLine++;
	}

	cout << endl;

	for (int col = 0; col <= 12; col++)
	{
		cout << setw(2) << col << " " << '|' << " ";
		for (int row = 0; row <= 12; row++)
		{
			displayRow = rowVar + row;
			cout << setw(2) << displayRow << " ";
		}
		rowVar++;
		cout << endl;
	}
}

void DisplayMultiplicationTable()
{
	int topRow = 0;
	int topLine = 0;
	int rowVar = 0;
	int displayRow = 0;

	cout << setw(5) << " ";

	while (topRow <= 12)
	{
		cout << setw(3) << topRow << " ";
		topRow++;
	}

	cout << endl;
	cout << "--------";

	while (topLine <= 12)
	{
		cout << "----";
		topLine++;
	}

	cout << endl;

	for (int col = 0; col <= 12; col++)
	{
		cout << setw(2) << col << " " << '|' << " ";
		for (int row = 0; row <= 12; row++)
		{
			displayRow = rowVar * row;
			cout << setw(3) << displayRow << " ";
		}
		rowVar++;
		cout << endl;
	}
}

[YokoTsuno]

This code has compilation errors (wrong variable names) but no linking errors if I correct the names.

[HatchetMan302]

Thx! It is fixed and running smoothly.