I'm building a class named Board, that will get it's details from a txt file.

#define ROW 25;
#define COL 80;
class Board
{
    char _board[ROW][COL] = {0};

public:
    Board(string name); // our new constructor - reads map from file.
};

It receives string name, and tries to open a file with the specific name. In case we are indeed in the right file, I want to read the chars from it, and copy them into a board. I've been trying several things, that are summed up in this code:

#include <iostream>
#include <fstream>
#include <string>
#include <sstream>
    Board::Board(string name)
{
    string line;
        ifstream file(name);
        int i = 0;
    if (file.is_open())
        {
            while (!file.eof())
            {
    
            (1) getline(file, line);
            (2) const char* test = line.c_str();
            (3) strcpy_s(_board[i], test);

        (4) _board[i] = line;

                    i  ;

            }
// MORE FUNCTIONS NOT RELEVANT TO THIS QUESTION
        }
}

I get the following errors: For (3): The program crashes. For (4): expression must be a modifiable lvalue. For (1), (2): test and line are worked well.

Is there any other simplier way to copy string to char* without using ugly loops, and copy every single char? Why is (3) crashing my program?

Thanks in advance!

CodePudding user response：

Unrelated, but void main() had been deprecated for ages and is incorrect in current versions of the standard: it shall be int main()...

Next while (!file.eof()) is a common but terrible thing: eof becomes true only after a reading operation returned nothing. That means that you will process the last line twice...

For your errors:

• (4) _board[i] is an array, and an array cannot be on the left size of an assignment (idiomatically: it is not a lvalue)

• (3): strcpy_s is not a drop-in replacement for strcpy and your compiler should have emit warnings (any correct compiler would have...). It should be:

    strcpy_s(_board[i], COL, test);
  

CodePudding user response：

#include <iostream>
#include <fstream>
#include <string>
#define ROW 25;
#define COL 80;
int i=0;
class Board
{
    char _board[ROW][COL] = {0};

public:
    Board(string name); // our new constructor - reads map from file.
};
Board::Board(string name)
{
   fstream newfile;

   newfile.open(name,ios::in); 

   if (newfile.is_open()){   

      string tp;
      while(getline(newfile, tp)){ 
        strcpy(_board[i], tp);
        i  ;
      }
      newfile.close(); 
   }
}