spdlog in CLion in 2022

 https://github.com/gabime/spdlog

Ubuntu new project, language standard use "C++17" or "C++14"

"Copy the include folder to your build tree and use a C++11 compiler" so that "include/spdlog/spdlog.h" exists

https://github.com/gabime/spdlog/tree/v1.x/include

CMakeLists.txt

cmake_minimum_required(VERSION 3.21)
project(untitled8)
set(CMAKE_CXX_STANDARD 17)
add_executable(untitled8 main.cpp)
include_directories("include")

main.cpp

#include <iostream>
int main() {
    std::cout << "Hello, World!" << std::endl;
    return 0;
}

Basic usage

#include "spdlog/spdlog.h"

int main() 
{
    spdlog::info("Welcome to spdlog!");
    spdlog::error("Some error message with arg: {}", 1);
    
    spdlog::warn("Easy padding in numbers like {:08d}", 12);
    spdlog::critical("Support for int: {0:d};  hex: {0:x};  oct: {0:o}; bin: {0:b}", 42);
    spdlog::info("Support for floats {:03.2f}", 1.23456);
    spdlog::info("Positional args are {1} {0}..", "too", "supported");
    spdlog::info("{:<30}", "left aligned");
    
    spdlog::set_level(spdlog::level::debug); // Set global log level to debug
    spdlog::debug("This message should be displayed..");    
    
    // change log pattern
    spdlog::set_pattern("[%H:%M:%S %z] [%n] [%^---%L---%$] [thread %t] %v");
    
    // Compile time log levels
    // define SPDLOG_ACTIVE_LEVEL to desired level
    SPDLOG_TRACE("Some trace message with param {}", 42);
    SPDLOG_DEBUG("Some debug message");
}

Comprehensive

CMakeList.txt

cmake_minimum_required(VERSION 3.21)
project(untitled8)
set(CMAKE_CXX_STANDARD 17)
add_executable(untitled8 main.cpp)
include_directories("include")

find_package (Threads REQUIRED)
target_link_libraries(untitled8 ${CMAKE_THREAD_LIBS_INIT})

main.cpp

#include <iostream>

// trace 0 > debug 1 > info 2 > warn 3 > error 4 > critical 5 > off 6
#define SPDLOG_ACTIVE_LEVEL SPDLOG_LEVEL_DEBUG

#include "spdlog/spdlog.h"
struct TempLogLevel {
    TempLogLevel(spdlog::level::level_enum newLevel = spdlog::level::debug) : oldLevel(spdlog::get_level()) {
        spdlog::set_level(newLevel);
    }
    ~TempLogLevel() {
        spdlog::set_level(oldLevel);
    }
private:
    spdlog::level::level_enum oldLevel;
};

// Basic usage
#include "spdlog/spdlog.h"
void basic() {
    spdlog::debug("This message should not be displayed..");

    spdlog::info("Welcome to spdlog!");
    spdlog::error("Some error message with arg: {}", 1);

    spdlog::warn("Easy padding in numbers like {:08d}", 12);
    spdlog::critical("Support for int: {0:d};  hex: {0:x};  oct: {0:o}; bin: {0:b}", 42);
    spdlog::info("Support for floats {:03.2f}", 1.23456);
    spdlog::info("Positional args are {1} {0}..", "too", "supported");
    spdlog::info("{:<30}", "left aligned");


    spdlog::set_level(spdlog::level::debug); // Set global log level to debug
    spdlog::debug("This message should be displayed..");
    spdlog::set_level(spdlog::level::info);

    // change log pattern
    //spdlog::set_pattern("[%H:%M:%S %z] [%n] [%^---%L---%$] [thread %t] %v");

    // Compile time log levels
    // define SPDLOG_ACTIVE_LEVEL to desired level
    SPDLOG_TRACE("Some trace message with param {}", 42);
    SPDLOG_DEBUG("see me if you #define SPDLOG_ACTIVE_LEVEL SPDLOG_LEVEL_DEBUG");

    SPDLOG_INFO("SPDLOG_INFO");
}

// Create stdout/stderr logger object
#include "spdlog/sinks/stdout_color_sinks.h"
void stdout_example()
{
    // create color multi threaded logger
    auto console = spdlog::stdout_color_mt("console");
    console->info("apple");
    auto err_logger = spdlog::stderr_color_mt("stderr");
    spdlog::get("console")->info("loggers can be retrieved from a global registry using the spdlog::get(logger_name)");
}

// Basic file logger
#include "spdlog/sinks/basic_file_sink.h"
void basic_logfile_example()
{
    try
    {
        auto logger = spdlog::basic_logger_mt("basic_logger", "logs/basic-log.txt");
        logger->info("spdlog::basic_logger_mt() to logs/basic-log.txt");
    }
    catch (const spdlog::spdlog_ex &ex)
    {
        std::cout << "Log init failed: " << ex.what() << std::endl;
    }
}

// Rotating files
#include "spdlog/sinks/rotating_file_sink.h"
void rotating_example()
{
    // Create a file rotating logger with 5mb size max and 3 rotated files
    auto max_size = 1048576 * 5; // 5242880
    auto max_files = 3;
    auto logger = spdlog::rotating_logger_mt("some_logger_name", "logs/rotating.txt", max_size, max_files);
    for (int i=0; i<1000*1000; ++i) {
        logger->info("time {}", time(nullptr));
    }
    // acutal file is 5242868, 12 bytes less than 5242880
    /*
-rw-rw-r-- 1 user user 5242868 3月   7 11:45 rotating.1.txt
-rw-rw-r-- 1 user user 5242868 3月   7 11:45 rotating.2.txt
-rw-rw-r-- 1 user user 5242868 3月   7 11:45 rotating.3.txt
-rw-rw-r-- 1 user user 5085584 3月   7 11:45 rotating.txt
     */
}

// Daily files
#include "spdlog/sinks/daily_file_sink.h"
void daily_example()
{
    // Create a daily logger - a new file is created every day on 2:30am
    auto logger = spdlog::daily_logger_mt("daily_logger", "logs/daily.txt", 2, 30);
}

// Backtrace support
void backtrace() {
    // Debug messages can be stored in a ring buffer instead of being logged immediately.
    // This is useful in order to display debug logs only when really needed (e.g. when error happens).
    // When needed, call dump_backtrace() to see them.

    spdlog::enable_backtrace(32); // Store the latest 32 messages in a buffer. Older messages will be dropped.
    // or my_logger->enable_backtrace(32)..
    for(int i = 0; i < 100; i++)
    {
        spdlog::debug("Backtrace message {}", i); // not logged yet..
    }
    // e.g. if some error happened:
    spdlog::dump_backtrace(); // log them now! show the last 32 messages

    // or my_logger->dump_backtrace(32)..
}

// Periodic flush
void periodic() {
    // periodically flush all *registered* loggers every 3 seconds:
    // warning: only use if all your loggers are thread safe ("_mt" loggers)
    spdlog::flush_every(std::chrono::seconds(3));
}

// Stopwatch
#include "spdlog/stopwatch.h"
void stopwatch_example()
{
    spdlog::stopwatch sw;
    int count = 0;
    for (int i=0; i<1000*1000; ++i) {
        count += i;
    }
    spdlog::debug("Elapsed {}", sw);
    spdlog::debug("Elapsed {:.3}", sw);
    spdlog::debug("Elapsed {:.9}s", sw);
    // need below in cmakes
//    find_package (Threads REQUIRED)
//    target_link_libraries(untitled8 ${CMAKE_THREAD_LIBS_INIT})
}

// Log binary data in hex
// many types of std::container<char> types can be used.
// ranges are supported too.
// format flags:
// {:X} - print in uppercase.
// {:s} - don't separate each byte with space.
// {:p} - don't print the position on each line start.
// {:n} - don't split the output to lines.
// {:a} - show ASCII if :n is not set.
#include "spdlog/fmt/bin_to_hex.h"
void binary_example()
{
    auto console = spdlog::get("console");
    std::array<char, 80> buf;
    console->info("Binary example: {}", spdlog::to_hex(buf));
    console->info("Another binary example:{:n}", spdlog::to_hex(std::begin(buf), std::begin(buf) + 10));
    // more examples:
    // logger->info("uppercase: {:X}", spdlog::to_hex(buf));
    // logger->info("uppercase, no delimiters: {:Xs}", spdlog::to_hex(buf));
    // logger->info("uppercase, no delimiters, no position info: {:Xsp}", spdlog::to_hex(buf));
}

// Logger with multi sinks - each with different format and log level
// create logger with 2 targets with different log levels and formats.
// the console will show only warnings or errors, while the file will log all.
void multi_sink_example()
{
    auto console_sink = std::make_shared<spdlog::sinks::stdout_color_sink_mt>();
    console_sink->set_level(spdlog::level::warn);
    console_sink->set_pattern("[multi_sink_example] [%^%l%$] %v");

    auto file_sink = std::make_shared<spdlog::sinks::basic_file_sink_mt>("logs/multisink.txt", true);
    file_sink->set_level(spdlog::level::trace);

    spdlog::logger logger("multi_sink", {console_sink, file_sink});
    logger.set_level(spdlog::level::debug);
    logger.warn("this should appear in both console and file");
    logger.info("this message should not appear in the console, only in the file");
}

// Asynchronous logging
#include "spdlog/async.h"
#include "spdlog/sinks/basic_file_sink.h"
void async_example()
{
    // default thread pool settings can be modified *before* creating the async logger:
    // spdlog::init_thread_pool(8192, 1); // queue with 8k items and 1 backing thread.
    auto async_file = spdlog::basic_logger_mt<spdlog::async_factory>("async_file_logger", "logs/async_log.txt");
    async_file->info("basic_logger_mt async_factory logs/async_log.txt");
    // alternatively:
    // auto async_file = spdlog::create_async<spdlog::sinks::basic_file_sink_mt>("async_file_logger", "logs/async_log.txt");
}

// Asynchronous logger with multi sinks
#include "spdlog/sinks/stdout_color_sinks.h"
#include "spdlog/sinks/rotating_file_sink.h"
void multi_sink_example2()
{
    spdlog::init_thread_pool(8192, 1);
    auto stdout_sink = std::make_shared<spdlog::sinks::stdout_color_sink_mt >();
    auto rotating_sink = std::make_shared<spdlog::sinks::rotating_file_sink_mt>("logs/multi_sink_example2.txt", 1024*1024*10, 3);
    std::vector<spdlog::sink_ptr> sinks {stdout_sink, rotating_sink};
    auto logger = std::make_shared<spdlog::async_logger>("loggername", sinks.begin(), sinks.end(), spdlog::thread_pool(), spdlog::async_overflow_policy::block);
    spdlog::register_logger(logger);
    logger->info("multi_sink_example2()");
}

// User defined types
// user defined types logging by implementing operator<<
#include "spdlog/fmt/ostr.h" // must be included
struct my_type
{
    int i;
    template<typename OStream>
    friend OStream &operator<<(OStream &os, const my_type &c)
    {
        return os << "[my_type i=" << c.i << "]";
    }
};
void user_defined_example()
{
    spdlog::get("console")->info("user defined type: {}", my_type{14});
}

// User defined flags in the log pattern
// Log patterns can contain custom flags.
// the following example will add new flag '%*' - which will be bound to a <my_formatter_flag> instance.
#include "spdlog/pattern_formatter.h"
class my_formatter_flag : public spdlog::custom_flag_formatter
{
public:
    void format(const spdlog::details::log_msg &, const std::tm &, spdlog::memory_buf_t &dest) override
    {
        std::string some_txt = "custom-flag";
        dest.append(some_txt.data(), some_txt.data() + some_txt.size());
    }

    std::unique_ptr<custom_flag_formatter> clone() const override
    {
        return spdlog::details::make_unique<my_formatter_flag>();
    }
};
void custom_flags_example()
{
    auto formatter = std::make_unique<spdlog::pattern_formatter>();
    formatter->add_flag<my_formatter_flag>('*').set_pattern("[%n] [%*] [%^%l%$] %v");
    spdlog::set_formatter(std::move(formatter));
}

// Custom error handler
#include "spdlog/sinks/syslog_sink.h"
void syslog_example()
{
    std::string ident = "spdlog-example";
    auto syslog_logger = spdlog::syslog_logger_mt("syslog", ident, LOG_PID);
    syslog_logger->warn("This is warning that will end up in syslog.");
    // tail -f /var/log/syslog
    /*
Mar  7 12:25:08 ricky-ryzen systemd[1440]: Starting Kite Updater...
Mar  7 12:25:10 ricky-ryzen spdlog-example[1578877]: This is warning that will end up in syslog.
Mar  7 12:25:10 ricky-ryzen systemd[1440]: kite-updater.service: Succeeded.
     */
}

// Android example
#ifdef __ANDROID__
#include "spdlog/sinks/android_sink.h"
void android_example()
{
    std::string tag = "spdlog-android";
    auto android_logger = spdlog::android_logger_mt("android", tag);
    android_logger->critical("Use \"adb shell logcat\" to view this message.");
}
#endif

// Load log levels from env variable or from argv
#include "spdlog/cfg/env.h"
int main_env()
{
    spdlog::cfg::load_env_levels();
    return 0;
}

// Load log levels from env variable or from argv
#include "spdlog/cfg/argv.h" // for loading levels from argv
int main_argv (int argc, char *argv[])
{
    // ./example SPDLOG_LEVEL=info,mylogger=trace
    // #include "spdlog/cfg/argv.h" // for loading levels from argv
    spdlog::cfg::load_argv_levels(argc, argv);
    return 0;
}

// Log file open/close event handlers
// You can get callbacks from spdlog before/after log file has been opened or closed.
// This is useful for cleanup procedures or for adding someting the start/end of the log files.
void file_events_example()
{
    // pass the spdlog::file_event_handlers to file sinks for open/close log file notifications
    spdlog::file_event_handlers handlers;
    handlers.before_open = [](spdlog::filename_t filename) { spdlog::info("Before opening {}", filename); };
    handlers.after_open = [](spdlog::filename_t filename, std::FILE *fstream) { fputs("After opening\n", fstream); };
    handlers.before_close = [](spdlog::filename_t filename, std::FILE *fstream) { fputs("Before closing\n", fstream); };
    handlers.after_close = [](spdlog::filename_t filename) { spdlog::info("After closing {}", filename); };
    auto my_logger = spdlog::basic_logger_st("some_logger", "logs/events-sample.txt", true, handlers);
}

// Replace the Default Logger
void replace_default_logger_example()
{
    auto new_logger = spdlog::basic_logger_mt("new_default_logger", "logs/new-default-log.txt", true);
    spdlog::set_default_logger(new_logger);
    spdlog::info("new logger log message");
}

int main(int argc, char *argv[])
{
    basic();
    stdout_example();
    basic_logfile_example();
    rotating_example();
    backtrace();
    periodic();
    stopwatch_example();
    binary_example();
    multi_sink_example();
    async_example();
    multi_sink_example2();
    user_defined_example();
    custom_flags_example();
    syslog_example();
#ifdef __ANDROID__
    android_example();
#endif
    main_env();
    main_argv(argc, argv);
    file_events_example();
    replace_default_logger_example();
    return 0;
}

End

End

End