A useful log4cpp example

The extremly expert implementation of log4cpp is unbalance by a very poor documentation. The test files provided in the distribution are not really that celebrating the features in a compact example. These following files shall be thought to help on that particular problem.

This example loads the properties file located below to init the log4cpp categories and illustrates some typical log4cpp idioms in intermingling your cpp code. Note that
the log stream log_sub1 will be written to the file "log4cpp_inited.log".

The include file names are not embraced properly - Blogger's templating. Modify if compiling fails.

Put the files into any folder and try to compile by something like:

g++ -gstabs+ -w -Iheaders log4cpp_inited.cpp -o log4cpp_inited.exe -llog4cpp

log4cpp_inited.cpp

#include "stdio.h"
#include "iostream"

#include "log4cpp/Category.hh"
#include "log4cpp/Appender.hh"
#include "log4cpp/OstreamAppender.hh"
#include "log4cpp/FileAppender.hh"
#include "log4cpp/Layout.hh"
#include "log4cpp/BasicLayout.hh"
#include "log4cpp/Priority.hh"
#include "log4cpp/NDC.hh"
#include "log4cpp/PropertyConfigurator.hh"

#define CODE_LOCATION __FILE__

// DEBUG < INFO < NOTICE < WARN < ERROR < CRIT < ALERT < FATAL = EMERG

#define LOG_EMERG(__logstream)  __logstream << log4cpp::Priority::EMERG << CODE_LOCATION
#define LOG_ALERT(__logstream)  __logstream << log4cpp::Priority::ALERT << CODE_LOCATION
#define LOG_CRIT(__logstream)  __logstream << log4cpp::Priority::CRIT << CODE_LOCATION
#define LOG_ERROR(__logstream)  __logstream << log4cpp::Priority::ERROR << CODE_LOCATION
#define LOG_WARN(__logstream)  __logstream << log4cpp::Priority::WARN << CODE_LOCATION
#define LOG_NOTICE(__logstream)  __logstream << log4cpp::Priority::NOTICE << CODE_LOCATION
#define LOG_INFO(__logstream)  __logstream << log4cpp::Priority::INFO << CODE_LOCATION
#define LOG_DEBUG(__logstream)  __logstream << log4cpp::Priority::DEBUG << CODE_LOCATION

int main(int argc, char** argv) 
{
    log4cpp::Category &log_root = log4cpp::Category::getRoot();
    log4cpp::Category &log_sub1 = log4cpp::Category::getInstance( std::string("log_sub1") );
    log4cpp::Category &log_sub2 = log4cpp::Category::getInstance( std::string("log_sub1.log_sub2") );

    const char *file_log4cpp_init = "log4cpp_inited.log4cpp_properties";

    try
      {
 log4cpp::PropertyConfigurator::configure( file_log4cpp_init );
      }
    catch( log4cpp::ConfigureFailure &e )
      {
 std::cout 
   << e.what() 
   << " [log4cpp::ConfigureFailure catched] while reading " 
   << file_log4cpp_init 
   << std::endl;

 exit(1);
      }
 
    std::cout << " root priority = " << log_root.getPriority() << std::endl;
    std::cout << " log_sub1 priority = " << log_sub1.getPriority() << std::endl;
    std::cout << " log_sub2 priority = " << log_sub2.getPriority() << std::endl;

    //root

    log_root.error("root error");
    log_root.warn("root warn");

    //log_sub1

    log_sub1.error("log_sub1 error");
    log_sub1.warn("log_sub1 warn");
    log_sub1.info("%s%d", "i = ", 1122334455 );
    log_sub1.log( log4cpp::Priority::NOTICE, "reopen log" );
    log_sub1.info("log reopened");
    log_sub1.warn("could not reopen log");

    //log_sub2

    log_sub2.error("log_sub2 error");
    log_sub2.warn("log_sub2 warn");
    log_sub2.warnStream() << "streamed warn";
 
    log_sub2 
      << log4cpp::Priority::WARN 
      << "warn2" 
      << " warn3" 
      << log4cpp::eol 
      << " warn4"
      ;

#define CODE_LOCATION "[end] "

    // the log stream is not compatible with an ostream. Here an example how
    // to still output everything as easy as to an ostream with the aid of an
    // ostringstream. Of course, performance will be relative poor for this construct.

    std::string obj( "word" );

    ostringstream log_stream_tmp << "exiting without a " << obj << endl;

    LOG_NOTICE(log_root) << log_stream_tmp.str();  
}

log4cpp_inited.log4cpp_properties

log4j.rootCategory=DEBUG, rootAppender
log4j.appender.rootAppender=org.apache.log4j.ConsoleAppender
log4j.appender.rootAppender.layout=org.apache.log4j.BasicLayout

log4j.category.log_sub1=NOTICE, A1
log4j.category.log_sub1.log_sub2=NOTICE, A2
log4j.additivity.category.log_sub1=false
              
log4j.appender.A1=org.apache.log4j.FileAppender
log4j.appender.A1.fileName=log4cpp_inited.log
log4j.appender.A1.layout=org.apache.log4j.PatternLayout
log4j.appender.A1.layout.ConversionPattern=%n %d [%t] %-5p %c - %m%n%n%n
       
log4j.appender.A2=org.apache.log4j.ConsoleAppender
log4j.appender.A2.layout=org.apache.log4j.PatternLayout
log4j.appender.A2.layout.ConversionPattern=%d [%t] %-5p %c - %m%n