#Preprocessor Timings

23 messages · Page 1 of 1 (latest)

worn fossil
#

If a CPP source file is including multiple .h - will the order will be to include first .h do its text substitutions and then include 2nd?

I'm getting error

g++ main.cpp -o production.out
In file included from map.h:11,
                 from main.cpp:1:
player.h: In function ‘int read_input(player*)’:
player.h:59:46: error: ‘WIDTH’ was not declared in this scope
   59 |         if (key=='d' && player_->position[X]<WIDTH-1) {
      |                                              ^~~~~
player.h:59:46: note: the macro ‘WIDTH’ had not yet been defined
In file included from main.cpp:1:
map.h:15: note: it was later defined here
   15 | #define WIDTH 5
      | 
In file included from map.h:11,
                 from main.cpp:1:
player.h:68:53: error: ‘HEIGHT’ was not declared in this scope
   68 |         else if (key == 's' && player_->position[Y]<HEIGHT-1) {
      |                                                     ^~~~~~
player.h:68:53: note: the macro ‘HEIGHT’ had not yet been defined
In file included from main.cpp:1:
map.h:16: note: it was later defined here
   16 | #define HEIGHT 5
      | 
make: *** [makefile:6: production] Error 1```


main.cpp is including first map.h then player.h

player.h
```cpp
#ifndef PLAYER_H
#define PLAYER_H

//#define DEBUG - Use compiler flag -D instead

#include <cstdint>
#include <termios.h>
#include <unistd.h>
#include <fcntl.h>

#include "map.h"
#include "constants.h"


/* Player Position */
#define X 0
#define Y 1

struct player {
    std::uint16_t position[2];
    int symbol;
};

...

#endif /*PLAYER_H*/

map.h

#ifndef MAP_H
#define MAP_H

#define clear_screen() write(STDOUT_FILENO, "\033[2J\033[H", 7);

#include <iostream>
#include <cstdint>
#include <unistd.h>

#include "debug.h"
#include "player.h"

/* MAP DIMENSIONS */
#define WIDTH 5
#define HEIGHT 5

/* BLOCKS */
#define WALL 0
#define WALKABLE 1
#define PLAYER 2

struct map {
    std::int16_t data[HEIGHT][WIDTH] = {0};
};

...

#endif /*MAP_H*/
balmy falconBOT
#

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hollow turtle
#

You could move those defines to another header. And im not sure if those circular includes are recommend.

worn fossil
hollow turtle
#

Can you send the whole code?

worn fossil
worn fossil
hollow turtle
#

There isnt a player.cpp or map.cpp?

worn fossil
#

it's a header only library

#

I will eventually split it but for learning the pitfalls I've merged it temporarily

hollow turtle
#

You also could use constexpr instead of defines. For learning purpose it is fine

#

What error messages you are getting after changing?

#

Maybe you miss the inline keyword? I only did header only libary with classes. There the keyword can be omitted.

worn fossil
# 
g++ main.cpp -o production.out
In file included from map.h:11,
                 from main.cpp:1:
player.h: In function ‘int read_input(player*)’:
player.h:59:46: error: ‘WIDTH’ was not declared in this scope
   59 |         if (key=='d' && player_->position[X]<WIDTH-1) {
      |                                              ^~~~~
player.h:59:46: note: the macro ‘WIDTH’ had not yet been defined
In file included from main.cpp:1:
map.h:15: note: it was later defined here
   15 | #define WIDTH 5
      | 
In file included from map.h:11,
                 from main.cpp:1:
player.h:68:53: error: ‘HEIGHT’ was not declared in this scope
   68 |         else if (key == 's' && player_->position[Y]<HEIGHT-1) {
      |                                                     ^~~~~~
player.h:68:53: note: the macro ‘HEIGHT’ had not yet been defined
In file included from main.cpp:1:
map.h:16: note: it was later defined here
   16 | #define HEIGHT 5
      | 
make: *** [makefile:6: production] Error 1
#

Unfortunately I'm not aware of the 2 keywrods that you mentioned

#

I know that separating the defines in a different header works - but why?

hollow turtle
#

This circular includes can be tricky sometimes. I guess it was defined multiple times. Or some other cause. You got include guards so maybe it wasnt defined multiple times. I dont know.

worn fossil
#

alrigthy - no worries - thanks for the help

hollow turtle
#

inline seems to be required

worn fossil
#

I will look into this

#

!solved