fstream: reading map

[clonxy]

I need help using <fstream> to read a file and input the map into a 2d vector
The map is:
map.txt

9
5
*********
**   ****
** ******
** u  ***
*********

The 9 is the columns, the 5 is the rows

object in cpp file

  std::ifstream fs;
  fs.open("map.txt");

  //checks to see if file exists
  if (fs.fail())
  {
  std::cerr << "Opening file failed.\n";
  }

  //inputs map into vector where first number is the column, second is the row
  int r,c;
  fs >> c;
  fs >> r;
  fs >> std::noskipws;
  fs.ignore(1);

  row = r;
  col = c;

  map2d.resize(c, std::vector<char>(r));  
  map2d[row][col];

  for (int i = 0; i < row; i++)
  {
    for (int j = 0; j < col+1; j++)
    {
      char ch;
      fs >> ch;
      // map2d[i][j] = ch;
    
      std::cout << ch;
    } 
  }
  fs.close();

whole cpp file

//David Chen
//Home Project 8

#include "Map.h"
#include <iostream>
#include <fstream>

/*
This was coded for the map below (assuming '*' = wall, 'u' = hero):

9
5
*********
**   ****
** ******
** u  ***
*********

  Map(); //constructor
  Map(string filename); //loads txt from filename and creates a map
  int Display() const; //displays map
  int Get(int row, int column) const; //gets row, col of character pos
  void Set(int row, int column, int new_value); //sets character from row,col to new value

*/

Map::Map() //default constructor that creates size of 0
{
  row = 0; //row/col for vector
  col = 0;
  char_pos_row = 0;
  char_pos_col = 0;
}

Map::Map(std::string filename) //loads txt from filename and creates a map
{
  std::ifstream fs;
  fs.open(filename);

  //checks to see if file exists
  if (fs.fail())
  {
  std::cerr << "Opening file failed.\n";
  }

  //inputs map into vector
  int r,c;
  std::cout << "map:" << std::endl;
  fs >> c;
  fs >> r;
  fs >> std::noskipws;
  fs.ignore(1);

  row = r;
  col = c;

  map2d.resize(c, std::vector<char>(r));  
  map2d[row][col];


/*
5x9
*********
**   ****
** ******
** u  ***
*********
*/

  for (int i = 0; i < row; i++)
  {
    for (int j = 0; j < col+1; j++)
    {
      char ch;
      fs >> ch;
      map2d[i][j] = ch;
    
      // std::cout << ch;
    } 
  }
  std::cout << map2d[0][0];
  fs.close(); //finished
}

void Map::Display() const//displays map
{
  std::cout << std::endl;

  for(int i = 0; i < row; i++)
  {
    for (int j = 0; j < col; j++)
    {
      std::cout << map2d[i][j];
    }
  std::cout << std::endl;
  }

}

char Map::Get(int r, int c)//method that returns the character at (row, column) position
{
  for (int i = 0; i < row; i++)
  {
    for (int j = 0; j < col; i++)
    {
      if(map2d[i][j] == 'u')
      map2d[i][j] = ' '; //deletes hero's old position.
    }
  }
  return map2d[r][c];
}

bool Map::is_char_pos_possible (int r, int c) //is the character position possible?
{
  if (char_pos_row > r || r < 0)
  {
    return false;
  }
  else if (char_pos_col > c || c < 0)
  {
    return false;
  }
  else if (map2d[r][c] == '*')
  {
    return false;
  }
  else 
  {
    return true;
  }
  for (int i = 0; i < row; i++)
  {
    for (int j = 0; j < col; j++)
    {
      if (map2d[r][c] == '*') //checks to see if char is trying to stand on the wall.
      {
        return false;
      }
    }
  }
}

void Map::Set(int r, int c, int new_value)//sets character from row,col to new value
{
  if (is_char_pos_possible(r,c) == true)
  {
    char_pos_row = r;
    char_pos_col = c;
    map2d[r][c] = new_value;
  }

}

Map::~Map(){} //deconstructor 

header file

//David Chen
//Home Project 8

#include <vector>
#include <string>

#ifndef Map_H
#define Map_H

class Map
{
  private:
  int row;
  int col;
  std::vector< std::vector<char> > map2d;
  int char_pos_row;
  int char_pos_col;

  public:
  Map(); //constructor, map size = 0
  Map(std::string filename); //loads txt from filename using fstream and creates a map
  void Display() const; //displays map, prints vector
  char Get(int r, int c); //method that returns the character at (row, column) position
  bool is_char_pos_possible(int r, int c);
  void Set(int row, int column, int new_value); //sets character from row,col to new value
  ~Map(); //deconstructor
};


#endif 

[SamuelAdams]

I have a few thoughts to share.

If your getting a error or something that's different, but assuming the file opens and reads the 1st char then continue reading...

So i'm looking for int main() but didn't find it.
I would create a function for loading the map.
Of course that's not required but might make things simpler later.

First you coded everything but didn't get the map right first....
Seems to me that should have been the first step.
I recommend starting a new program just to work on reading the map to keep other issues from being a issue until you can read the map 100% of the time.
By making it in a function, you can just add that to this code when complete.

Second.
Seems like your making it harder than it has to be.
Since you know the size is X*Y or in this case 5x9, why not just read in 9 char's
go to the next line read in 9 chars and do that 5 times ??

So at this time I suggest make a program to read the file, and then print it out.
Add the other code afterwards such as "is_char_pos_possible"

PS. I like all your comments.

[clonxy]

I found the solution. Here it is for people that need it:

//David Chen
//Home Project 8

#include "Map.h"
#include <fstream>

Map::Map() //default constructor that creates size of 0
{
  row = 0; //row/col for vector
  col = 0;
  char_pos_row = 0;
  char_pos_col = 0;
}

Map::Map(std::string filename) //loads txt from filename and creates a map
{
  std::ifstream fs;
  fs.open(filename);

  //checks to see if file exists
  if (fs.fail())
  {
  std::cerr << "Opening file failed.\n";
  }

  //inputs map into vector
  int r,c;
  fs >> c;
  fs >> r;
  fs >> std::noskipws;
  fs.ignore(1);

  row = r;
  col = c;

  map2d.resize(c, std::vector<char>(r));  
  map2d[row][col];

  for (int i = 0; i < row; i++)
  {
    for (int j = 0; j <=  col; j++)
    {
      char ch;
      fs >> ch;
      map2d[i][j] = ch;
      // std::cout << map2d[i][j]; //debugging
    }
  }
  fs.close(); //finished
}

void Map::Display() const//displays map
{
  std::cout << "Display: "<< std::endl;

  for(int i = 0; i < row; i++)
  {
    for (int j = 0; j < col; j++)
    {
      std::cout << map2d[i][j];
    }
  std::cout << std::endl;
  }

}

char Map::Get(int r, int c)//method that returns the character at (row, column) position
{
  return map2d[r][c];
}

bool Map::is_in_board (int r, int c) //is the position inside the vector?
{
  if (r >= row || r < 0)
  {
    return false;
  }
  else if (c >= col || c < 0)
  {
    return false;
  }
  else 
  {
    return true;
  }
}

void Map::Set(int r, int c, char new_value)//sets character in row,col to new value
{
  if (is_in_board(r,c) == true)
  {
    char_pos_row = r;
    char_pos_col = c;
    map2d[char_pos_row][char_pos_col] = new_value;
  }

}

Map::~Map(){} //deconstructor 

main.cpp file (for testing purposes):

//David Chen
//Home Project 8
#include "Map.h"

using namespace std;

int main() 
{

  Map ms("map.txt");

  ms.Map::Display();

  std::cout << ms.Map::Get(3,3) << std::endl;

  ms.Map::Set(0,0,'A');

  ms.Map::Display();
  
}

Map.h header file:

//David Chen
//Home Project 8
#include <iostream>
#include <vector>
#include <string>

#ifndef Map_H
#define Map_H

class Map
{
  private:
  int row;
  int col;
  std::vector< std::vector<char> > map2d;
  int char_pos_row;
  int char_pos_col;

  public:
  Map(); //constructor, map size = 0
  Map(std::string filename); //loads txt from filename using fstream and creates a map
  void Display() const; //displays map, prints vector
  char Get(int r, int c); //method that returns the character at (row, column) position
  bool is_in_board(int r, int c);
  void Set(int row, int column, char new_value); //sets character at row,col to new_value
  ~Map(); //deconstructor
};


#endif