Quelle est la différence entre c logger et d’autres bibliothèques de journalisation comme log4c ou nglogc ?

c logger se distingue par sa simplicité et sa légèreté. Elle ne propose pas autant de fonctionnalités que d’autres bibliothèques plus complètes, mais elle couvre les besoins essentiels de la journalisation. Elle est également compatible avec le standard C89 et thread-safe.

Comment faire pour afficher les messages de log dans un autre format que le texte ?

c logger ne supporte que le format texte pour les messages de log. Si vous voulez utiliser un autre format, comme le JSON ou le XML, vous devrez écrire votre propre fonction de formatage et l’appeler dans la fonction logger.

Comment faire pour filtrer les messages de log en fonction du tag ou du niveau ?

c logger ne propose pas de filtrage avancé des messages de log. Vous pouvez seulement contrôler le niveau global des messages avec la variable log_level dans le fichier de configuration. Si vous voulez filtrer les messages en fonction du tag ou du niveau, vous devrez écrire votre propre fonction de filtrage et l’appeler dans la fonction logger.

Comment faire pour envoyer les messages de log vers une autre destination que la console ou le fichier ?

c logger ne supporte que la console et le fichier comme destinations pour les messages de log. Si vous voulez envoyer les messages vers une autre destination, comme une base de données ou un service web, vous devrez écrire votre propre fonction d’envoi et l’appeler dans la fonction logger.

Comment faire pour déboguer c logger en cas de problème ?

c logger fournit une fonction logger_debug qui affiche des informations sur l’état interne de la bibliothèque. Vous pouvez l’appeler à tout moment pour vérifier si c logger fonctionne correctement.

What is “c logger” and how to use it?

Francis

c logger is a simple and efficient logging library for the C language . It allows you to write log messages to a file or to the console, with different levels of detail and control. In this article, we will see what features C logger offers, how to install it and use it in your C projects.

C logger features

c logger is a lightweight library, which is only 500 lines of source code. It is compatible with the C89 standard and is thread-safe. It offers two types of logging:

Console logging, which displays log messages in standard or error output.
Logging to file, which writes log messages to a text file, with automatic rotation based on file size.

c logger also allows you to customize logging with a configuration file, in which you can define the message format, the level of detail, the name of the log file, the maximum file size, etc.

How to install c logger?

To install c logger, simply download the source code from the GitHub repository and compile it with your favorite C compiler. For example, with gcc:

$ git clone https://github.com/yksz/c-logger.git $ cd c-logger $ gcc -c -o logger.o logger.c $ ar rcs libclogger.a logger.o

This will create a static libclogger.a archive that you can link to your C program. You will also need to include the logger.h header file in your source files.

How to use clogger?

To use c logger, you must first initialize the library with the logger_init , passing it the name of the configuration file or NULL if you want to use the default parameters. logger function to write log messages, passing it a tag, a level and a message. For example :

#include "logger.h" int main(void) { /* Initialize the library with the config.ini file */ if (logger_init("config.ini") != 0) { fprintf(stderr, "Initialization error of c logger\n"); return 1; } /* Write an INFO level message with the tag "main" */ logger("main", LOG_INFO, "Start of program"); /* Write an ERROR level message with the tag "main" */ logger("main", LOG_ERROR, "Fatal error"); /* End library */ logger_end(); return 0; }

The format of log messages depends on the configuration file used. By default, it is of the form:

date-time tag message level

For example :

2023-06-13 02:37:16 main INFO Start of program 2023-06-13 02:37:16 main ERROR Fatal error

The format can be modified using the following variables in the configuration file:

%d: the date in YYYY-MM-DD format
%t: time in HH:MM:SS format
%c: the message tag
%l: message level
%m: the message
%n: a line break

For example, if we want to have a shorter format, we can use:

[formats] simple = "%t %c %l %m%n"

What levels of detail are available?

c logger offers five levels of detail for log messages:

LOG_DEBUG: for debug messages, useful for developers.
LOG_INFO: for informative messages, useful for users.
LOG_WARN: for warning messages, useful for reporting abnormal but non-critical situations.
LOG_ERROR: for error messages, useful for reporting critical situations that prevent the program from functioning properly.
LOG_FATAL: for fatal messages, useful for reporting unrecoverable situations that require stopping the program.

You can control the level of detail of log messages using the log_level in the configuration file. For example, if we want to display only ERROR and FATAL level messages, we can use:

[general] log_level = 3

Levels are numbered 0 to 4, from most detailed to least detailed. By default, the level is 0, which displays all messages.

How to control the size of the log file?

c logger allows you to limit the size of the log file by using the max_file_size in the configuration file. For example, if we want the log file to not exceed 1 MB, we can use:

[general] max_file_size = 1048576

The size is expressed in bytes. By default, there is no size limit.

When the log file reaches the maximum size, c logger creates a new file with a numeric suffix. For example, if the log file name is log.txt , the first file created will be log.txt.1 , then log.txt.2 , etc. The maximum number of files created is controlled by the max_file_count in the configuration file. For example, if we want to keep a maximum of 10 log files, we can use:

[general] max_file_count = 10

By default, there is no limit on the number of files.

FAQs

What is the difference between c logger and other logging libraries like log4c or nglogc?

c logger stands out for its simplicity and lightness. It doesn't have as many features as other, more comprehensive libraries, but it covers the essential logging needs. It is also compatible with the C89 and thread-safe standard.

How do I display log messages in a format other than text?

c logger only supports text format for log messages. If you want to use another format, such as JSON or XML, you will need to write your own formatting function and call it in the logger .

How to filter log messages based on tag or level?

c logger does not offer advanced filtering of log messages. You can only control the overall message level with the log_level in the configuration file. If you want to filter messages based on tag or level, you will need to write your own filter function and call it in the logger .

How do I send log messages to a destination other than the console or the file?

c logger only supports console and file as destinations for log messages. If you want to send the messages to another destination, such as a database or web service, you will need to write your own send function and call it in the logger .

How to debug c logger in case of problem?

c logger provides a logger_debug that displays information about the internal state of the library. You can call it at any time to check if c logger is working properly.

Conclusion

c logger is a simple and efficient logging library for the C language. It allows you to write log messages to a file or to the console, with different levels of detail and control. It is easy to install and use, and offers customization with a configuration file. c logger is based on the principle of object-oriented programming , which allows you to create logger objects with specific properties and methods. c logger is an ideal solution for developers who want to add logging functionality to their C projects without the hassle.