How to use this by initializing outside main() function so as to make it available to be used in other functions defined in a cpp file.

[Jargon4072]

I want to initialize it outside the main() function so as I can use it in the other functions present in the file. For example, the initialization process is as below:

const auto logFile = "file_test.log";
L::init(logFile);
L::enableEchoMode(true);
L::setLoggingLevel(L::Level::Trace); 

I want to use it as given below:

#include "../../simple_logger.hpp"

// Don't compile asserts away
#ifdef NDEBUG
    #undef NDEBUG
#endif

#include <cassert>
#include <cstdlib>
#include <fstream>
using namespace std;
using juzzlin::L;

const auto logFile = "file_test.log";
L::init(logFile);
L::enableEchoMode(true);
L::setLoggingLevel(L::Level::Trace);
const std::string timestampSeparator = " ## ";
L::setTimestampMode(L::TimestampMode::DateTime, timestampSeparator);

void foo(string name){
     L().info() << "Recived name is: "+name+".";
     court<<"Hello World "<<name<<endl;
     L().info() << "Exiting foo()";
}
int main(){
    const std::string message = "Hello, world!";
    L().trace() << message;
    L().debug() << message;
    L().info() << message;
    L().warning() << message;
    L().error() << message;
    L().fatal() << message;
    return 0;
}

I am getting errors as shown below:

How to fix this?

[juzzlin]

The problem here is that your code is not valid C++. You cannot call functions outside the call stack initiating from main():

int someFunction()
{
  return 0;
}

someFunction();
^^^^^ This is not legal.

const auto logFile = "file_test.log";
L::init(logFile);
^^^^^ This is not legal.

int main()
{
  return 0;
}

Once you have initialized the logger in main() you can use it from any function so I'm not sure what the actual problem is :) These are global initializations, not per function.

Your code should be something like this:

#include "../../simple_logger.hpp"

// Don't compile asserts away
#ifdef NDEBUG
    #undef NDEBUG
#endif

#include <cassert>
#include <cstdlib>
#include <fstream>

using juzzlin::L;

void foo(string name) {
     L().info() << "Recived name is: " << name << ".";
     std::cout << "Hello World " << name << std::endl;
     L().info() << "Exiting foo()";
}

void bar(string name) {
     L().info() << "Recived name is: " << name << ".";
     std::cout << "Hello World " << name << std::endl;
     L().info() << "Exiting bar()";
}

int main() {
    // Just init the logger once here. This will always be called before foo() and bar().
    const auto logFile = "file_test.log";
    L::init(logFile);
    L::enableEchoMode(true);
    L::setLoggingLevel(L::Level::Trace);
    const std::string timestampSeparator = " ## ";
    L::setTimestampMode(L::TimestampMode::DateTime, timestampSeparator);

    const std::string message = "Hello, world!";
    L().trace() << message;
    L().debug() << message;
    L().info() << message;
    L().warning() << message;
    L().error() << message;
    L().fatal() << message;
    
    return 0;
}

[Jargon4072]

Thanks for pointing that out. I was actually looking to use this in a library coded in c++ which doesn't have main() in it. I ended up coding a basic logger by myself :).

[juzzlin]

Note that the initialization doesn't have to be exactly in main. It can be in any function that's being called first, like some library initialization function 😊