CLogger (clog)

A lightweight, macro-based logging library for C with support for multiple log levels and automatic uppercase/lowercase function naming.

⚠️ Note: Due to the use of specific macros, C++ compatibility is not guaranteed. This library is designed for C projects.

Features

• Log levels: DEBUG, INFO, WARNING, ERROR, CRITICAL
• Simple macros to define logging functions automatically
• Prints log level in uppercase while allowing lowercase function names
• Easily extendable by modifying the LOG_LEVELS macro
• Minimal dependencies — works with standard C (stdio.h)

Installation

1. Include clog.h and define CLOG:

#define CLOG

#include "clog.h"

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Usage

Initialize a logger

CLogger logger = init_clog(.level=DEBUG);

If .level is not passed the used level will be INFO.

Logging messages

Use the automatically generated logging functions:

clog_debug(logger, "This is a debug message");
clog_info(logger, "This is an info message");
clog_warn(logger, "This is a warning message");
clog_err(logger, "This is an error message");
clog_crit(logger, "This is a critical message");

• Functions are generated via macros from the LOG_LEVELS macro.
• The printed log level is always uppercase:

[DEBUG] This is a debug message
[INFO] This is an info message
[WARNING] This is a warning message

Customization

The log levels and function names are defined in clog.h:

#define LOG_LEVELS(X) \
    X(DEBUG, debug)   \
    X(INFO, info)     \
    X(WARNING, warn)  \
    X(ERROR, err)     \
    X(CRITICAL, crit)

• First parameter → enum constant (uppercase)
• Second parameter → function suffix (lowercase)

You can add or remove levels easily by editing this macro.

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Example

#include "clog.h"

int main() {
    CLogger logger = init_clog(.level=WARNING);

    clog_debug(logger, "Debug message");    // Will not print
    clog_info(logger, "Info message");      // Will not print
    clog_warn(logger, "Warning message");   // Will print

    return 0;
}

Output:

[WARNING] Warning message

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License

MIT License. Free to use and modify.