C++: Read text file into 2d array - c++

Question

I'm trying to read the following maze.txt file:
35
35
0
10
++++++++++S++++++++++++++++++++++++
++++++++++OOOOOOOOOOOOOOOOOOOOOOOOO
++++++++++O++++++++++++++++++O+++++
OOOOOOOOOOOOOOOOOOOOOOOOOO+++O++OOE
O+++++++++O++++++++++++++O+++O++O++
OOOOOO++++O++++++++++++++O+++O++O++
O++++O++++OOOOOOOOOOO++++O+OOO++O++
O++++O++++O+++++++++OOOO+O+++O++O++
OOO++OOOO+OOOOOO+++++++++++OOO++OOO
O+O+++++O++++++OOOOOOOOOO++O++++++O
O+OOOO++O++++++O++++++++O+++OOO+++O
O++++O++OOOOOOOO++++++++O+++O+O+++O
OOO++O++++++++++++++++++OOOOO+O+++O
++O++OOOOOOOOOOOOOOOO+++++++++OO++O
OOO+++++++++++++++++OOOOOO++++++++O
O++++++++++++++++++++++++O++OOOOOOO
+++++++++++++++++++++++++O++O++++++
OOOOOOOOOOOOOOOOOOOOOOOOOO++OOOOO++
O++++++++++++++++++++++++O++++++O++
OOOOOOO+++++++++++++++OOOOOOO+++O++
++++++++++++++++++++++O+++++OO++O++
OOOOOOOOOOOOOOOOOOOOOOO++++++O++O++
O++++++++++++++++++++++++++++O+OOOO
OOOO++++++++++++++++++++OOOOOO+O+++
+++OOOOOOOOO+++++++++++++++++++O+++
+++++O+++++OOOOOOOOOO++++++++OOO+++
+O+++OOOOO++++++O++++++++++++O+++++
+OOOOO+++O++++++OOOOOO+++++++O+++++
+++++++++++++++++++++OOOOOOOOO+++++
OOOOOOOOOOOOOOOOOOOOOO+++++++++++++
+++++++++++++++++++++++++++++++++++
+++++++++++++++++++++++++++++++++++
+++++++++++++++++++++++++++++++++++
+++++++++++++++++++++++++++++++++++
+++++++++++++++++++++++++++++++++++
The code works fine with the maze inside the code but I moved it out to a text file, which seems to be read but it is not working. It's giving me the error:
No matching function for call to 'mazeTravel'.
I'm not sure where to go from here. Any help would be appreciated!
#include <iostream>
#include <fstream>
using namespace std;
void printMaze(const char maze[][12], int xCoordinate, int yCoordinate);
int mazeTravel(char maze[][12], int xCoordinate, int yCoordinate, int direction);
int main()
{
char maze[35][35];
ifstream file;
file.open("maze.txt");
if (!file) {
cout << "Error reading file\n";
return -1;
}
else {
for (int row = 0; row < 35; row++) {
for (int column = 0; column < 35; column++) {
file >> maze[row][column];
int success = 0;
success = mazeTravel(maze, 2, 0, 1);
if (success == 1)
cout << "The maze has been solved.\n";
else
cout << "Sorry, the maze cannot be solved\n";
}
}
}
return 0;
}

Answer 1

You could use a std::vector of std::strings to represent your maze:
std::vector<std::string> maze;
To access its cells use
maze[row][column]; // with row being y and column x
To get the number of rows use
maze.size()
and
maze[0].size()
for the number of columns.
You could read such a maze like that (without error checking to not clutter the code):
std::vector<std::string> readMaze(std::istream &is)
{
std::size_t columns;
std::size_t rows;
is >> columns >> rows;
int foo; // sorry, don't know what the 3rd and 4th
is >> foo >> foo; // number is. a starting position, perhaps?
// ignore the rest of the current line:
is.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
std::string line;
std::vector<std::string> maze;
while (std::getline(is, line))
maze.push_back(line);
return maze;
}
An implementation (with error checking) could look like that:
#include <cstdlib> // EXIT_FAILURE
#include <limits> // std::numeric_limits<>
#include <vector>
#include <string>
#include <fstream>
#include <iostream>
// to not have to type std::vector<std::string> all over the place
using maze_type = std::vector<std::string>;
void printMazeCell(maze_type const &maze, std::size_t x, std::size_t y)
{
std::cout.put(maze[y][x]);
}
void printMaze(maze_type const &maze)
{
for (auto const &row : maze)
std::cout << row << '\n';
}
int mazeTravel(maze_type const &maze, std::size_t x, std::size_t y, int dir)
{
// access cells of the maze with maze[y][x]
// maze.size() for the number of columns and
// maze[0].size() for the number of rows
return 42;
}
maze_type readMaze(std::istream &is)
{
std::size_t columns;
if (!(is >> columns)) {
std::cerr << "Couldn't read the number of columns :(\n\n";
return maze_type{}; // return an empty maze on error
}
std::size_t rows;
if (!(is >> rows)) {
std::cerr << "Couldn't read the number of rows :(\n\n";
return maze_type{};
}
int foo;
is >> foo >> foo; // sorry, don't know what the 3rd and 4th number is
// ignore the rest of the current line:
is.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
std::cout << "Trying to read a maze with " << columns << " columns ...\n";
std::string line;
maze_type maze;
while (std::getline(is, line)) {
if (line.length() != columns) {
std::cerr << "Found a row that contains only "
<< line.length() << " columns :(\n\n";
return maze_type{};
}
maze.push_back(line);
}
if (maze.size() != rows) {
std::cerr << "The maze only consists of "
<< maze.size() << " rows :(\n\n";
return maze_type{};
}
return maze;
}
int main()
{
char const *filename = "maze.txt";
std::ifstream is{ filename };
if (!is.is_open()) {
std::cerr << "Couldn't open \"" << filename << "\" for reading :(\n\n";
return EXIT_FAILURE;
}
maze_type maze = readMaze(is);
if (!maze.size()) { // readMaze returned an empty maze :(
std::cerr << "Bye.\n";
return EXIT_FAILURE;
}
printMaze(maze);
}

Answer 2

The problem that you don't have the implementation of
int mazeTravel(char maze[][12], int xCoordinate, int yCoordinate, int direction);
You should create the implementation like this:
int mazeTravel(char maze[][12], int xCoordinate, int yCoordinate, int direction)
{
// The implementation
return 0;
}
Another thing: You have to read the first some numbers at the beginning of the file.
35
35
0
10
After that you can read the matrix from the file