Opening file using user input

[JM567]

Hello! I am writing a code for a checkers game and I need to give the user the option to either start a new game, or continue their saved game. We have two text files, one called "newGame.txt" and one called "savedGame.txt". Once the user chooses, fileName is assigned to that file and needs to be opened. Right now I'm getting errors and I'm not sure how to properly assign fileName to the file since this isn't working. If anybody has any advice that would help a lot!

char gameType;
    std::string fileName;
    
    std::cout << "Create new game or continue saved game?" << std::endl << "N or S" << std::endl;
    std::cin >> gameType;
    if(gameType == 'N')  {
        fileName = "newGame.txt";
	// Open new game here
        }
    if(gameType == 'S') {
        fileName = "savedGame.txt";
	// Open saved game here
        }

[jonnin]

its a lot to retype, try this and if you still don't get it ask specific questions, or tell us what errors you are seeing exactly.

http://www.cplusplus.com/doc/tutorial/files/

[JM567]

The errors I'm getting all say "call to non-static member function without an object argument". So it seems like the assignment for fileName isn't working properly

[doug4]

I'm getting errors and I'm not sure how to properly assign fileName to the file since this isn't working

You need to be much more specific. What errors are you getting? What isn't working?

Is this your actual code, or did you just cut out a small snippet for your post and then further edit your snippet?

It is very difficult to diagnose problems in code that is not shown in your post.

One thing, though, is that the reason you assign the variable fileName is so you can have a single place to open your game file and read in the data. So, the structure of your code would make more sense if it were:

    if(gameType == 'N')  {
        fileName = "newGame.txt";
    }
    else if(gameType == 'S') {
        fileName = "savedGame.txt";
    }
    else {
        // handle error here
    }

    // open game file here 

I doubt this is the problem you are seeing, but, again, we haven't seen your error messages.

[jlb]

And what line does the error message refer to and is this the only error message being generated?

[doug4]

The errors I'm getting all say "call to non-static member function without an object argument". So it seems like the assignment for fileName isn't working properly

Nothing in your post suggests this problem. Please post your whole code and also post the actual build output.

[Duthomhas]

Nah, you only need an if. Also, your question is too complex. Simplify, man. (Or woman, if you are...)

  std::ifstream f;
  {
    std::cout << "Continue saved game? ";
    std::string s;
    getline( std::cin, s );
    // (The first non-whitespace character must be a 'Y' or 'y':
    auto n = s.find_first_not_of( " \t\n\r\v" );
    if (n != s.npos and std::toupper( s[ n ] ) == 'Y')
      f.open( "savedGame.txt" );
    else 
      f.open( "newGame.txt" );
  }
  if (f) ...

A comment, though: why do you have to open a file for a new game?

You should be creating your gameboard/game state in-memory when the program starts. Only if the user wishes to continue a saved game do you need to open a file and use it to set the gameboard/game state.

Hope this helps.

[JM567]

Here is my entire code. I did change the portion I posted so it uses string now, however that doesn't affect the errors I'm given. All of the errors state: "call to non-static member function without an object argument" and they are lines 256, 302, 304, 305:

// 
// 
// Lab 05 - Checkers Program

// Compile with clang++ -Wall -std=c++11 checkersLab05.cpp

#include <iostream>
#include <sstream>
#include <fstream>
#include <string>
#include <cstring>
#include <cstdlib>

enum ChipColor {      // value as int EMPTY==0 RED==1 BLACK==2
	EMPTY, RED, BLACK
};
enum ChipRank {    // value as int NOTKING==0 KING==1
	NOTKING, KING
};

enum SquareColor {   // value as int WHITE_SQUARE=0 BLACK_SQUARE=1
        WHITE_SQUARE, BLACK_SQUARE
};

// Square class defines a square on a checkers board 
class Square{

    public:
        Square();
        Square(ChipColor newColor, ChipRank newRank, SquareColor newSqColor); 
        void setColor(ChipColor newColor);
        void setRank(ChipRank newRank);
        void setSquareColor(SquareColor newSqColor);
        ChipColor getChipColor();
        char displayChipColor();
        char saveChipColor();
        char saveChipRank();
        char saveSquareColor();

    private:
        ChipColor chipColor;
        ChipRank chipRank;
        SquareColor squareColor;
};

// Your square member function code goes here        

Square::Square(){
        chipColor = EMPTY;
        chipRank = NOTKING;
        squareColor = WHITE_SQUARE;
}
        

Square::Square(ChipColor newColor, ChipRank newRank, SquareColor newSqColor){ 
        chipColor = newColor;
        chipRank = newRank;
        squareColor = newSqColor;
}

void Square::setColor(ChipColor newColor){
        chipColor = newColor;
}


void Square::setRank(ChipRank newRank){
        chipRank = newRank;
}

void Square::setSquareColor(SquareColor newSqColor){
        squareColor = newSqColor;
}


ChipColor Square::getChipColor(){
    return chipColor;
}

char Square::displayChipColor(){

    char color;
   
    if (chipColor == EMPTY)
        color = ' ';
    if (chipColor == RED)
        color = 'R';
    if (chipColor == BLACK)
        color = 'B';

    return color;
}

char Square::saveChipColor(){

    char color;
   
    if (chipColor == EMPTY)
        color = '0';
    if (chipColor == RED)
        color = '1';
    if (chipColor == BLACK)
        color = '2';

    return color;
}

char Square::saveChipRank()  {
    
    char rank;
    
    if(chipRank == NOTKING)
        rank = '0';
    if(chipRank == KING)
        rank = '1';
        
    return rank;
    }
    
char Square::saveSquareColor()  {
    
    char color;
    
    if(squareColor == WHITE_SQUARE)
        color = '0';
    if(squareColor == BLACK_SQUARE)
        color = '1';
        
    return color;
    }


// Board class defines an 8x8 board
class Board {
    
    public:
        Board();
        void displayBoard();
        void setupBoard(std::string fileName);
        void SaveBoard(std::string fileName);
 
    private:
        int boardSize = 8;
        Square board[8][8];
};


// Your Board member function code goes here        


Board::Board(){
    
   int i=0;
   int j=0;
   int color;
    
   for (i=0; i<boardSize; ++i){
       color = (i) % 2;          // Mod 2 - needed to distinguish white and black squares
       for (j=0; j<boardSize; ++j){
          if ( (j + color) %2 ){
              board[i][j].setSquareColor(WHITE_SQUARE); 
          }
          else{
              board[i][j].setSquareColor(BLACK_SQUARE); 
          }
      }
   }
}



// This function is provided for you
//
// display an 8x8 board of squares like the following:
//
//  +-----+-----+-----+...
//  |*****|     |*****|
//  |* x *|     |* x *|
//  |*****|     |*****|
//  +-----+-----+-----+...
//
//   where the square with the x in it is a black square where the x indicates the color (empty, R or B) 
//   and the blank squares are just spaces; 

void Board::displayBoard(){
   std::string dashes = "+-----";      //characters for square top and bottom bounds
   std::string spaces = "|     ";      //fill for white squares
   std::string stars = "|*****";       // fill for black squares
   std::string line = "";
   std::string filler;
   int i,j,color;
 
    for (i=0; i < boardSize; i++){   //repeat 8 times, once for each row of squares 
        
        line="";  
        for (j=0; j < boardSize; j++){     //build line of cells for boundary  ( +---+ )
            line = line + dashes;
        }
        std::cout << line << "+" << std::endl;
        
        color = (i) % 2;          // Mod 2 - needed to distinguish white and black squares

        line="";                       
        for (j=0; j < boardSize; j++){     //build first line for row of square
            if ( (j + color) %2 ){
                filler = spaces;        // fill spaces for white squares    ( |   |)
            }
            else{
                filler = stars;        // fill stars for black squares     ( |***|)
            }
            line = line + filler;
        }

        std::cout << line << "|" << std::endl;
      

        line="";
        for (j=0; j < boardSize; j++){             //build second line for row of square ( | x | )
            if ((j + color) % 2 ){
               filler = spaces;        // fill spaces for white squares    ( |   |)
            }
            else{
               filler = "|**";                   // fill spaces for blacksquares
               filler += board[i][j].displayChipColor();   // display color of checker
               filler += "**";          
          }
          line = line + filler;
        }
        std::cout << line << "|" << std::endl;
      
        line="";
        for (j=0; j < boardSize; j++){              //build third line for row of square 
           if ( (j + color) %2 ){
                filler = spaces;        // fill spaces for white squares   ( |   | )
            }
            else{
                filler = stars;        // fill stars for black squares   ( |***| )
            }
            line = line + filler;
        }
        std::cout << line << "|" << std::endl;
   }
   

        line="";  
        for (j=0; j < boardSize; j++){     //build line of cells for boundary on bottom of board   ( +---+ )
            line = line + dashes;
        }
        std::cout << line << "+" << std::endl;
        
        std::cout << std::endl;

}

void Board::setupBoard(std::string fileName)   {
    std::ifstream inf;
    inf.open(fileName);
    if(!inf.is_open())   {
        std::cout << "Sorry, could not open file." << std::endl;
	    exit(0);
    }
}

void Board::SaveBoard(std::string fileName)   {
    std::ofstream fout;
    fout.open(fileName);
    if(!fout)   {
        std::cout << "Sorry could not save game." << std::endl;
        exit(0);
        }
    for (int i = 0; i < 8; i++)  {
        for (int j = 0; j < 8; j++)  {
            fout << board[i][j].saveChipColor() << ' ';
            fout << board[i][j].saveChipRank() << ' ';
            fout << board[i][j].saveSquareColor() << ' ';
            fout << "0";
            fout << std::endl;
        }
    }
    fout.close();
    return;
}

 
int main(){
    
    Board gameBoard;
    
    gameBoard.displayBoard();
    
    std::ifstream inputFile;
    std::string fileName;
    
    std::cout << "Please enter the file name:" << std::endl << "newGame.txt or savedGame.txt" << std::endl;
    getline(std::cin, fileName);
    inputFile.open(fileName);
    if(!inputFile.is_open())    {
        std::cout << "Sorry, could not load game." << std::endl;
        exit(0);
        }
    
    gameBoard.setupBoard(fileName);
    
    gameBoard = Board::SaveBoard(fileName);
    Board::SaveBoard(fileName);

   
    Square firstSquare;
    Square secondSquare(RED, NOTKING, BLACK_SQUARE);

    std::cout  <<  firstSquare.getChipColor() << std::endl;  
    std::cout  <<  secondSquare.getChipColor() << std::endl;
    
    return 0;

}

[jlb]

Looks like you're not compiling using C++11 (or higher). Check your compiler settings, using a std::string for the open() of a file stream wasn't added until C++11.

[LajosOnly]

In Line 254 you're opening a ifstream in a method.
This ifstream isn't a static object, it will be lost after this method!
You should close your data-sessions after using.

Do you want to check your file twice? Maybe you should check Line 257 and 296!

[Thomas1965]

gameBoard = Board::SaveBoard(fileName);
Board::SaveBoard(fileName);

class Board doesn't have a static function SaveBoard.
Also why do you call it twice ?

There are also some warnings that should be fixed.

main.cpp(120): warning C4701: potentially uninitialized local variable 'rank' used
main.cpp(94): warning C4701: potentially uninitialized local variable 'color' used
main.cpp(108): warning C4701: potentially uninitialized local variable 'color' used
main.cpp(132): warning C4701: potentially uninitialized local variable 'color' used

[doug4]

Thank-you for posting your entire code. Now we can see that the location of the errors you mentioned in your first post are not related to the lines of code you posted in your first post.

All of the errors state: "call to non-static member function without an object argument" and they are lines 256, 302, 304, 305:

I think you still edited your code a little bit from the original. The error message locations your provided (again, we would prefer the actual messages pasted into your post rather than you retyping them) don't line up with the code you provided. Specifically, lines 302 and 305 are blank lines.

Line 301 (which I'm guessing lines up with error line 302) does have an object, so I don't see how that can map to the error message you provided.

The error line 256 probably lines up with code line 256. Again, there is an object here, so I don't see how that can map to the error message you provided. As previous posters said, you need to either use C++11 or change inf.open(fileName); to inf.open(fileName.c_str());. But that is not really a member function without an object situation.

Edit: By the way, I went to the online compiler (click the gear symbol next to your code) and compiled your code. I only got error messages for lines 303 and 304 (related to your error lines 304 and 305). I didn't see your other errors.