Errors When Compiling Multiple .hpp and .cpp Files in c++ - c++

Question

I just started a CS degree and I'm brand new to actual programming and hence the implementation is proving difficult. I recently had an assignment that left me stumped. I was stumped because I was unable to link all the files together (2 header files .hpp and 2 implementation files .cpp). The assignment has come and gone I'm just curious as to how I would link all the files together since I know that when it comes to compile time the Board.hpp and Board.cpp files will compile into one file and the TicTacToe.hpp and TicTacToe.cpp files will compile into one file AND then all of the two compiled files will be linked to each other to produce the executable file.
Here is the error I get when I try to compile in g++:
TicTacToe.hpp:1:9: warning: #pragma once in main file
/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64/crt1.o: In function `_start':
(.text+0x20): undefined reference to `main'
collect2: ld returned 1 exit status
I have no idea what any of that means.
I'll post the files below for your reviewing. I appreciate any help you can give. Again, I'm brand new at this so if you could explain things simply I would really appreciate it.
Board.hpp
#ifndef BOARD_HPP
#define BOARD_HPP
#include <iostream>
#include <string>
class TTTBoard
{
private:
char Board[3][3]; //creates array
int play(); // prototype for play function
void makeMove(); //prototype for makeMove function
int turn(int); //prototype for turn function
int check(int, int); //prototypr for check function
void print(char x[][3]); //prototype for print function
int gameState(char x[][3]); //prototype for gameState fuction
int player1, player2, draw, player, winner, done; //creates variables to be used.
int row, col; //creates variables to be used in gamestate function
public:
int TtlGames, TtlP1, TtlP2, TtlDraws; //creates variables that will define gamestate
void intBoard(); //prototype for intboard
};
#endif
The next one is kind of long.
Board.cpp
#include "Board.hpp"
#include <iostream>
#include <iomanip>
void TTTBoard::intBoard() //function to initialize the board
{ //initialzes the variables in order
done = false; // to be used for later functions
winner = 0;
player = 2;
player1 = 1;
player2 = 2;
draw = 3;
int i, k;
for (k = 0; k<3; k++) //initializes array to 0
{
for (i = 0; i<3; i++)
{
Board[k][i] = 0;
}
}
play(); //begins the game
}
int TTTBoard::check(int row, int col) //checks if spot if occupied
{
if (Board[row][col] == 0)
{
return true;
}
else if (Board[row][col] != 0)
{
std::cout << "That square is already taken.";
return false;
}
else
{
std::cout << "Checking for win.";
gameState(Board);
}
return false;
}
void TTTBoard::makeMove() //records players move
{
player = turn(player);
int answer = false;
while (answer == false)
{
std::cout << "Player" << turn(player) << ": please enter your move\n";
std::cin >> row, col;
answer = check(row, col);
}
if (player == 1)
Board[row][col] = 'X';
else if (player == 2)
Board[row][col] = 'O';
else
std::cout << "Failed.";
}
int TTTBoard::gameState(char x[][3]) //checks for a win or a draw
{
winner = 0;
int count = 0;
int a = row;
int b = col;
for (a = 0; a<3; a++)
{
for (b = 0; b<3; b++)
{
if (Board[a][b] == 0)
{
count++;
}
}
}
if (count > 0)
{
int row, col, xCheck, oCheck;
for (row = 0; row<3; row++)
{
xCheck = 0;
oCheck = 0;
for (col = 0; col<3; col++)
{
if (x[row][col] == 'X')
xCheck++;
if (x[row][col] == 'O')
oCheck++;
if (oCheck == 3)
{
winner = 2;
}
if (xCheck == 3)
{
winner = 1;
}
}
}
for (col = 0; col<3; col++)
{
xCheck = 0;
oCheck = 0;
for (row = 0; row<3; row++)
{
if (x[row][col] == 'X')
xCheck++;
if (x[row][col] == 'O')
oCheck++;
if (oCheck == 3)
{
winner = 2;
}
if (xCheck == 3)
{
winner = 1;
}
}
}
if (x[0][0] == 'X' && x[1][1] == 'X' && x[2][2] == 'X')
{
winner = 1;
}
else if (x[0][0] == 'O' && x[1][1] == 'O' && x[2][2] == 'O')
{
winner = 2;
}
else if (x[2][0] == 'X' && x[1][1] == 'X' && x[0][2] == 'X')
{
winner = 1;
}
else if (x[2][0] == 'O' && x[1][1] == 'O' && x[0][2] == 'O')
{
winner = 2;
}
}
else if (count == 9)
{
std::cout << "Its a draw.";
winner = 3;
}
else
{
std::cout << "It is the next players turn\n\n";
}
if (winner > 0)
{
done = true;
}
return done;
}
void TTTBoard::print(char Board[][3]) //prints current board state
{
std::cout << "\n";
std::cout << " 0 1 2\n";
std::cout << "0 " << Board[0][0] << " " << Board[0][1] << " " << Board[0][2] << " \n";
std::cout << "1 " << Board[1][0] << " " << Board[1][1] << " " << Board[1][2] << " \n";
std::cout << "2 " << Board[2][0] << " " << Board[2][1] << " " << Board[2][2] << " \n";
}
This one is also long.
TicTacToe.hpp
#ifndef TICTACTOE_HPP
#define TICTACTOE_HPP
#include "Board.hpp"
#include <iostream>
#include <string>
#include <iomanip>
class Board; //creates a board to be forward declared
class TicTacToe //creates tictactoe class
{
private:
int check(int, int);
int turn(int player);
int play(); //prototype for play method
int gameState(char x[][3]);
public:
int TtlGames, TtlP1, TtlP2, TtlDraws;
void intBoard();
Board* playBoard; //forward declarations for use in functions
Board* print;
Board* makeMove;
Board* BoardT;
};
#endif
TicTacToe.cpp
#include "Board.hpp"
#include "TicTacToe.hpp"
#include <iostream>
#include <string>
void TTTBoard::intBoard() //initializes board
{
done = false;
winner = 0;
player = 2;
player1 = 1;
player2 = 2;
draw = 3;
int i, k;
for (k = 0; k<3; k++)
{
for (i = 0; i<3; i++)
{
Board[k][i] = 0;
}
}
play();
}
int TicTacToe::turn(int player) //informs players of whose turn it is.
{
switch (player)
{
case 1: player = 2;
{
std::cout << "\nPlayers 1 turn.\n\n";
break;
}
case 2: player = 1;
{
std::cout << "\nPlayers 2 turn.\n\n";
break;
}
}
return player;
}
int TTTBoard::gameState(char x[][3]) //checks for win or draw
{
winner = 0;
int count = 0;
int a = row;
int b = col;
for (a = 0; a<3; a++)
{
for (b = 0; b<3; b++)
{
if (Board[a][b] == 0)
{
count++;
}
}
}
if (count > 0)
{
int row, col, xCheck, oCheck;
for (row = 0; row<3; row++)
{
xCheck = 0;
oCheck = 0;
for (col = 0; col<3; col++)
{
if (x[row][col] == 'X')
xCheck++;
if (x[row][col] == 'O')
oCheck++;
if (oCheck == 3)
{
winner = 2;
}
if (xCheck == 3)
{
winner = 1;
}
}
}
for (col = 0; col<3; col++)
{
xCheck = 0;
oCheck = 0;
for (row = 0; row<3; row++)
{
if (x[row][col] == 'X')
xCheck++;
if (x[row][col] == 'O')
oCheck++;
if (oCheck == 3)
{
winner = 2;
}
if (xCheck == 3)
{
winner = 1;
}
}
}
if (x[0][0] == 'X' && x[1][1] == 'X' && x[2][2] == 'X')
{
winner = 1;
}
else if (x[0][0] == 'O' && x[1][1] == 'O' && x[2][2] == 'O')
{
winner = 2;
}
else if (x[2][0] == 'X' && x[1][1] == 'X' && x[0][2] == 'X')
{
winner = 1;
}
else if (x[2][0] == 'O' && x[1][1] == 'O' && x[0][2] == 'O')
{
winner = 2;
}
}
else if (count == 9)
{
std::cout << "Its a draw.";
winner = 3;
}
else
{
std::cout << "It is the next players turn\n\n";
}
if (winner > 0)
{
done = true;
}
return done;
}
int TicTacToe::play() //initializes the game
{
int done = false;
Board* print(Board);
while (!done)
{
int count = 0;
Board* makeMove();
Board* (Board);
count++;
if (count != 9)
{
return !done;
}
else
{
done = true;
}
}
return 0;
}
int main() //main method
{
TicTacToe playGame;
playGame.TtlGames = 0, playGame.TtlP1 = 0,
playGame.TtlP2 = 0, playGame.TtlDraws = 0; //counters for total games, Player 1 Total,
int Winner = 0; //Player 2 Total , and Total draws.
char done = false;
while (!done)
{
// This will display before each game
std::cout << "Let's play a game of TicTacToe\n\n";
// Play a game and remember who won (if anyone)
playGame.intBoard();
}
// Finish
std::cout << "\n\nThank you for playing!\n";
std::cin.get();
std::cin.get();
return 0;
}
I attempted the suggestion by Code Fuller but it gave me this error.
/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64/crt1.o: In function `_start':
(.text+0x20): undefined reference to `main'
collect2: ld returned 1 exit status
So I thought maybe if I put the Main method in a separate file and link them all it might work. I got this:
/tmp/ccmSwwUz.o: In function `TTTBoard::intBoard()':
TicTacToe.cpp:(.text+0x0): multiple definition of `TTTBoard::intBoard()'
/tmp/ccSwOY9D.o:Board.cpp:(.text+0x0): first defined here
/tmp/ccmSwwUz.o: In function `TTTBoard::gameState(char (*) [3])':
TicTacToe.cpp:(.text+0x104): multiple definition of `TTTBoard::gameState(char (* ) [3])'
/tmp/ccSwOY9D.o:Board.cpp:(.text+0x288): first defined here
/tmp/ccSwOY9D.o: In function `TTTBoard::intBoard()':
Board.cpp:(.text+0xa7): undefined reference to `TTTBoard::play()'
/tmp/ccSwOY9D.o: In function `TTTBoard::makeMove()':
Board.cpp:(.text+0x176): undefined reference to `TTTBoard::turn(int)'
Board.cpp:(.text+0x19b): undefined reference to `TTTBoard::turn(int)'
/tmp/ccmSwwUz.o: In function `TTTBoard::intBoard()':
TicTacToe.cpp:(.text+0xa7): undefined reference to `TTTBoard::play()'
/tmp/ccz4019v.o: In function `main':
Main.cpp:(.text+0x48): undefined reference to `TicTacToe::intBoard()'
collect2: ld returned 1 exit status
So then I tried compiling the Board into an object first then linking TicTacToe and Main:
g++ Board.o TicTacToe.cpp Main.cpp -o TTT
and got the following errors:
/tmp/cc9h5kAs.o: In function `TTTBoard::intBoard()':
TicTacToe.cpp:(.text+0x0): multiple definition of `TTTBoard::intBoard()'
Board.o:Board.cpp:(.text+0x0): first defined here
/tmp/cc9h5kAs.o: In function `TTTBoard::gameState(char (*) [3])':
TicTacToe.cpp:(.text+0x104): multiple definition of `TTTBoard::gameState(char (*) [3])'
Board.o:Board.cpp:(.text+0x288): first defined here
Board.o: In function `TTTBoard::intBoard()':
Board.cpp:(.text+0xa7): undefined reference to `TTTBoard::play()'
Board.o: In function `TTTBoard::makeMove()':
Board.cpp:(.text+0x176): undefined reference to `TTTBoard::turn(int)'
Board.cpp:(.text+0x19b): undefined reference to `TTTBoard::turn(int)'
/tmp/cc9h5kAs.o: In function `TTTBoard::intBoard()':
TicTacToe.cpp:(.text+0xa7): undefined reference to `TTTBoard::play()'
/tmp/ccZlZ4Dn.o: In function `main':
Main.cpp:(.text+0x48): undefined reference to `TicTacToe::intBoard()'
collect2: ld returned 1 exit status

Answer 1

You trying to compile Board.cpp to executable file while it doesn't contain 'main' entrypoint. You have to compile Board.cpp to object file first:
gcc Board.cpp -c
Then you can compile TicTacToe.cpp and link it with Board.o:
gcc Board.o TicTacToe.cpp -o TicTacToe