Clog

A simple, versatile logging library for C

About

Clog is a logging library that's designed to be as straightforward as possible to use from the get-go. It avoids any sort of dynamic memory allocation and gives the user a clear interface for setting and checking the properties used by the internal logging function. It has a hierarchical log severity level similar to many other libraries, along with additional features such as colored console output and max file size rollover.

Getting Started

The sample program below demonstrates nearly all of the functionality the library has to offer.

#include "clog.h"

int main(int argc, char *argv[]) {
  int i;

  // Initialize the internal ClLogProps instance to sensible defaults. This is the first and only 
  // needed to get going.
  ClInitLogProps();

  // A simple message.
  LOG_INFO("This is a basic logging message.");

  // Format substituion similar to built-in functions like printf().
  LOG_INFO("This message includes %d substitutions, similar to how %s work.", 2, 
           "printf(), fprintf(), etc.");

  // Different colors for each severity level.
  LOG_FATAL("This is a fatal message with magenta coloring.");
  LOG_ERROR("This is an error message with red coloring.");
  LOG_WARN("This is a warning message with orange coloring.");
  LOG_INFO("This is an information message with green coloring.");

  // The default level property value is CL_LOG_LEVEL_INFO, thus this won't print.
  LOG_DEBUG("This is a debugging message (that never gets printed).");

  // Change the level property to print all levels of messages.
  ClSetPropLevel(CL_LOG_LEVEL_ALL);
  LOG_DEBUG("This is a debugging message with blue coloring.");
  LOG_TRACE("This is a tracing message with cyan coloring.");

  // Set a filename. Since the stream property is set to CL_STREAM_ALL by default, it will begin
  // printing to both the console and the file.
  ClSetPropFilename("demo.log");
  LOG_INFO("This will be printed to the console, as well as \"demo.log\" as its first entry.");

  // Now we'll change the stream property temporarily so we're only printing to the file, and 
  // change the rollover property to 1024 bytes. Then we'll force a log rollover to occur.
  ClSetPropStream(CL_STREAM_DISK);
  ClSetPropRollover(1024);
  for(i = 0; i < 7; i++) {
    LOG_INFO("This message is 116 characters long including the info that comes before it.");
  }
  LOG_INFO("This message will cause the file to exceed the rollover value, which triggers it to "
           "be closed and renamed with an incremental number appended to it. A new file with the "
           "original filename is then opened and used in its place.");
  LOG_INFO("This message will be the first message in the new log file.");

  ClSetPropStream(CL_STREAM_ALL);
  LOG_INFO("This concludes the feature demo for Clog!");

  // Cleanup the internal ClLogProps instance safely.
  ClResetLogProps();

  return 0;
}

All of these functions and more are available for getting, setting, and controlling the output of the library. For full documentation on the API check out docs/, and for more sample programs check out examples/.