Configuration files
These functions are declared in the main Allegro header file:
#include <allegro5/allegro.h>Allegro supports reading and writing of configuration files with a simple, INI file-like format.
A configuration file consists of key-value pairs separated by
newlines. Keys are separated from values by an equals sign
(=). All whitespace before the key, after the value and
immediately adjacent to the equals sign is ignored. Keys and values may
have whitespace characters within them. Keys do not need to be unique,
but all but the last one are ignored.
The hash (#) character is used a comment when it is the
first non-whitespace character on the line. All characters following
that character are ignored to the end of the line. The hash character
anywhere else on the line has no special significance.
Key-value pairs can be optionally grouped into sections, which are
declared by surrounding a section name with square brackets
([ and ]) on a single line. Whitespace before
the opening bracket is ignored. All characters after the trailing
bracket are also ignored.
All key-value pairs that follow a section declaration belong to the last declared section. Key-value pairs that don’t follow any section declarations belong to the global section. Sections do not nest.
Here is an example configuration file:
# Monster description
monster name = Allegro Developer
[weapon 0]
damage = 443
[weapon 1]
damage = 503It can then be accessed like this (make sure to check for errors in an actual program):
ALLEGRO_CONFIG* cfg = al_load_config_file("test.cfg");
printf("%s\n", al_get_config_value(cfg, "", "monster name")); /* Prints: Allegro Developer */
printf("%s\n", al_get_config_value(cfg, "weapon 0", "damage")); /* Prints: 443 */
printf("%s\n", al_get_config_value(cfg, "weapon 1", "damage")); /* Prints: 503 */
al_destroy_config(cfg);ALLEGRO_CONFIG
typedef struct ALLEGRO_CONFIG ALLEGRO_CONFIG;An abstract configuration structure.
Examples:
ALLEGRO_CONFIG_SECTION
typedef struct ALLEGRO_CONFIG_SECTION ALLEGRO_CONFIG_SECTION;An opaque structure used for iterating across sections in a configuration structure.
See also: al_get_first_config_section, al_get_next_config_section
Examples:
ALLEGRO_CONFIG_ENTRY
typedef struct ALLEGRO_CONFIG_ENTRY ALLEGRO_CONFIG_ENTRY;An opaque structure used for iterating across entries in a configuration section.
See also: al_get_first_config_entry, al_get_next_config_entry
Examples:
al_create_config
ALLEGRO_CONFIG *al_create_config(void)Create an empty configuration structure.
See also: al_load_config_file, al_destroy_config
Examples:
al_destroy_config
void al_destroy_config(ALLEGRO_CONFIG *config)Free the resources used by a configuration structure. Does nothing if passed NULL.
See also: al_create_config, al_load_config_file
Examples:
al_load_config_file
ALLEGRO_CONFIG *al_load_config_file(const char *filename)Read a configuration file from disk. Returns NULL on error. The configuration structure should be destroyed with al_destroy_config.
See also: al_load_config_file_f, al_save_config_file
Examples:
al_load_config_file_f
ALLEGRO_CONFIG *al_load_config_file_f(ALLEGRO_FILE *file)Read a configuration file from an already open file.
Returns NULL on error. The configuration structure should be destroyed with al_destroy_config. The file remains open afterwards.
See also: al_load_config_file
al_save_config_file
bool al_save_config_file(const char *filename, const ALLEGRO_CONFIG *config)Write out a configuration file to disk. Returns true on success, false on error.
See also: al_save_config_file_f, al_load_config_file
Examples:
al_save_config_file_f
bool al_save_config_file_f(ALLEGRO_FILE *file, const ALLEGRO_CONFIG *config)Write out a configuration file to an already open file.
Returns true on success, false on error. The file remains open afterwards.
See also: al_save_config_file
al_add_config_section
void al_add_config_section(ALLEGRO_CONFIG *config, const char *name)Add a section to a configuration structure with the given name. If the section already exists then nothing happens.
al_remove_config_section
bool al_remove_config_section(ALLEGRO_CONFIG *config, char const *section)Remove a section of a configuration.
Returns true if the section was removed, or false if the section did not exist.
Since: 5.1.5
Examples:
al_add_config_comment
void al_add_config_comment(ALLEGRO_CONFIG *config,
const char *section, const char *comment)Add a comment in a section of a configuration. If the section doesn’t yet exist, it will be created. The section can be NULL or “” for the global section.
The comment may or may not begin with a hash character. Any newlines in the comment string will be replaced by space characters.
See also: al_add_config_section
al_get_config_value
const char *al_get_config_value(const ALLEGRO_CONFIG *config,
const char *section, const char *key)Gets a pointer to an internal character buffer that will only remain valid as long as the ALLEGRO_CONFIG structure is not destroyed. Copy the value if you need a copy. The section can be NULL or “” for the global section. Returns NULL if the section or key do not exist.
See also: al_set_config_value
Examples:
al_set_config_value
void al_set_config_value(ALLEGRO_CONFIG *config,
const char *section, const char *key, const char *value)Set a value in a section of a configuration. If the section doesn’t yet exist, it will be created. If a value already existed for the given key, it will be overwritten. The section can be NULL or “” for the global section.
For consistency with the on-disk format of config files, any leading and trailing whitespace will be stripped from the value. If you have significant whitespace you wish to preserve, you should add your own quote characters and remove them when reading the values back in.
See also: al_get_config_value
Examples:
al_remove_config_key
bool al_remove_config_key(ALLEGRO_CONFIG *config, char const *section,
char const *key)Remove a key and its associated value in a section of a configuration.
Returns true if the entry was removed, or false if the entry did not exist.
Since: 5.1.5
Examples:
al_get_first_config_section
char const *al_get_first_config_section(ALLEGRO_CONFIG const *config,
ALLEGRO_CONFIG_SECTION **iterator)Returns the name of the first section in the given config file.
Usually this will return an empty string for the global section, even it
contains no values. The iterator parameter will receive an
opaque iterator which is used by al_get_next_config_section
to iterate over the remaining sections.
The returned string and the iterator are only valid as long as no change is made to the passed ALLEGRO_CONFIG.
See also: al_get_next_config_section
Examples:
al_get_next_config_section
char const *al_get_next_config_section(ALLEGRO_CONFIG_SECTION **iterator)Returns the name of the next section in the given config file or NULL
if there are no more sections. The iterator must have been
obtained with al_get_first_config_section
first.
See also: al_get_first_config_section
Examples:
al_get_first_config_entry
char const *al_get_first_config_entry(ALLEGRO_CONFIG const *config,
char const *section, ALLEGRO_CONFIG_ENTRY **iterator)Returns the name of the first key in the given section in the given
config or NULL if the section is empty. The iterator works
like the one for al_get_first_config_section.
The returned string and the iterator are only valid as long as no change is made to the passed ALLEGRO_CONFIG.
See also: al_get_next_config_entry
Examples:
al_get_next_config_entry
char const *al_get_next_config_entry(ALLEGRO_CONFIG_ENTRY **iterator)Returns the next key for the iterator obtained by al_get_first_config_entry.
The iterator works like the one for al_get_next_config_section.
Examples:
al_merge_config
ALLEGRO_CONFIG *al_merge_config(const ALLEGRO_CONFIG *cfg1,
const ALLEGRO_CONFIG *cfg2)Merge two configuration structures, and return the result as a new configuration. Values in configuration ‘cfg2’ override those in ‘cfg1’. Neither of the input configuration structures are modified. Comments from ‘cfg2’ are not retained.
See also: al_merge_config_into
al_merge_config_into
void al_merge_config_into(ALLEGRO_CONFIG *master, const ALLEGRO_CONFIG *add)Merge one configuration structure into another. Values in configuration ‘add’ override those in ‘master’. ‘master’ is modified. Comments from ‘add’ are not retained.
See also: al_merge_config