CODEWITHSUNDEEP
cpointersstructglobal
Henrique Ferrolho
Henrique Ferrolho

Reputation: 942

How to define global pointer to struct in C?

I am trying to define a global pointer to a struct - font - so I can use it whenever I need it along my project.

When I compile, I get this error initializer element is not constant at line Font_t* font = load_font("ubuntu"); of Font.c.

Font.h:

#ifndef __FONT_H
#define __FONT_H

#include "Bitmap.h"
#include "Utilities.h"

/// Represents a Font
typedef struct {
    int letterSpacing;

    // symbols
    Bitmap_t* space;
    (...)
    Bitmap_t* y;
    Bitmap_t* z;
} Font_t;
extern Font_t* font;

/**
 * @brief Loads a font from disk
 *
 * @param filename name of the font to load
 */
Font_t* load_font(char const* fontName);

Font.c:

#include "Font.h"

#include "stdio.h"
#include "Utilities.h"
#include "video_gr.h"

Font_t* font = load_font("ubuntu");

Font_t* load_font(char const* fontName) {
    Font_t* font = (Font_t*) malloc(sizeof(Font_t));

    font->letterSpacing = 1;

    char path[200];
    strcpy(path, fontsPath);
    strcat(path, fontName);

    char tempPath[200];

    strcpy(tempPath, path); strcat(tempPath, "/space.bmp"); font->space = load_bitmap(tempPath);
    (...)
    strcpy(tempPath, path); strcat(tempPath, "/y.bmp"); font->y = load_bitmap(tempPath);
    strcpy(tempPath, path); strcat(tempPath, "/z.bmp"); font->z = load_bitmap(tempPath);

    return font;
}

Upvotes: 1

Views: 1878

Answers (4)

Danvil
Danvil

Reputation: 23031

You can do something like this to keep the initialization of your font in the font module.

Header:

// extern Font_t* font; // delete this
Font_t* get_default_font(); // use a function instead

Source:

Font_t* g_default_font = NULL;

Font_t* get_default_font() {
   if(!font) {
       g_default_font = load_font("ubuntu");
   }
   return g_default_font;
}

Upvotes: 2

Alok Save
Alok Save

Reputation: 206646

Font_t* font = load_font("ubuntu");

You cannot do that. You are not allowed to call functions this way in global scope. You will need to split the declaration and the initialization.

At global scope:

Font_t* font;

On first use, inside main:

font = load_font("ubuntu");

Upvotes: 3

mcleod_ideafix
mcleod_ideafix

Reputation: 11448

You cannot initialize a global variable with something which is not a constant value. Place this line:

font = load_font("ubuntu");

In your code, before any other code that tries to use font.

And leave as global declaration only this line:

Font_t* font = NULL;

Upvotes: 1

user2760375
user2760375

Reputation: 2568

Are you using this outside all functions

Font_t* font = load_font("ubuntu");

if so ,I don't think you will be able to do so ??

Upvotes: 0

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