Question

EDIT: I also got an answer to make sector a vector of vectors:

vector<vector<char>>sector;

and that gets rid of the rest of my errors.

EDIT: I’ve made sector an array of pointers as someone suggested, and still get three errors:

EDIT: I have edited the program, but it has not fixed all of the errors:

I have this section of a program:

char* load_data(int begin_point,int num_characters);
ifstream mapdata("map_data.txt");
const int maxx=atoi(load_data(0,2));
const int maxy=atoi(load_data(2,2));
char** sector=new char[maxx][maxy];

char* load_data(int begin_point,int num_characters)
{
    seekg(begin_point);
    char* return_val=new char[num_characters+1];
    mapdata.getline(return_val,num_characters);
    return return_val;
}

And I get these errors:

line 5>error C2540: non-constant expression as array bound

line 5>error C2440: ‘initializing’ : cannot convert from ‘char (*)[1]’ to ‘char **’

line 14>error C3861: ‘seekg’: identifier not found

per seekg: yes I know I have to include fstream, I included that in main.cpp, this is a separate .h file also included in main.cpp.

How do I fix the errors? Specifically, how to I fix the errors while keeping all my variables global?

Also, if it helps, this is map_data.txt:

10
10
00O
99!

1
55X
19
What is a question?
18
This is an answer
1
1
2
1

Answer 1

Well,

function load_data(int,int) returns a char.
You are passing that char to the atoi function, that takes a char*. In addition to that, you are probably not including stdlib.h header file!!

#include <cstdlib>
int atoi(const char*);

If you dont wan’t to include stdlib.h, then you could declare atoi as extern, but be aware when you compile this module.

extern int atoi(const char*)

Take into account that the argument of atoi function must be a null-terminated string.

In order for your code to work, you should make function load data return a char*, not a char.

char* load_data(int,int);

So, now you could do

//notice these aren't const, they rely on non-compile time available data.
int maxx = atoi (load_data(....));
int maxy = atoi (load_data(....));

If you are in C++, load_data function could return a std::string.

std::string load_data(int,int)

and then use c_str() method, which returns a C-String from a C++ string.

   const char* std::string:c_str()


    int maxx = atoi(load_data(....).c_str());
    int maxy = atoi(load_data(....).c_str());

In addition to that, you shouldn’t

(regarding

line 5>error C2540: non-constant expression as array bound

line 5>error C2440: 'initializing' : cannot convert from 'char (*)[1]' to 'char **'

)

char sector[maxx][maxy]; 

You should

 char** sector = new char[maxx][maxy]();

and dont forget to free this memory

delete[](sector);