helper.cpp

#include "helper.h"

string my_pad_right(string const& str, int length, char c)
{
    if ( str.size() < length )
        return str + string(length - str.size(), c);
    else
        return str;
}

string my_pad_left(string const& str, int length, char c)
{
    if ( str.size() < length )
        return std::string(length - str.size(), c) + str;
    else
        return str;
}


// Cross-platform (Windows, Unix) sleep function
void my_sleep(int milliseconds) 
{
#ifdef _WIN32
	Sleep(milliseconds);
#else
	usleep(milliseconds * 1000);
#endif
}

void my_log(string str, string log_level)
{
	time_t tmNow;
	tmNow = time(NULL);
	struct tm t = *localtime(&tmNow);
	string date_time =   my_pad_left(to_string(t.tm_mday       ), 2, '0') + "/"
	                   + my_pad_left(to_string(t.tm_mon +     1), 2, '0') + "/"
					   + my_pad_left(to_string(t.tm_year + 1900), 4, '0') + " "
					   + my_pad_left(to_string(t.tm_hour       ), 2, '0') + ":"
					   + my_pad_left(to_string(t.tm_min        ), 2, '0') + ":"
					   + my_pad_left(to_string(t.tm_sec        ), 2, '0');
	//printf("%s", date_time.c_str()); //For printf you need a c-style string
	
	int pid, ppid;
	
#ifdef _WIN32
	pid = ::GetCurrentProcessId();
#else
	pid  = ::getpid();
	ppid = ::getppid();
#endif

	cout << "[" << date_time << "][PID:" << pid << "][PPID:" << ppid << "]" << log_level << " " << str << endl;
}

helper.h

// This is a protection to avoid cross duplidated when many sources include this .h file 
#ifndef _HELPER_
#define _HELPER_


#include <iostream>       // for using std
#include <string>         // for using std::string
#include <ctime>          // for using time
#ifdef _WIN32
    #include <windows.h>  // for using Sleep() on Windows
#else
    #include <unistd.h>   // for using usleep() on Unix
#endif // _WIN32


using std::cout;
using std::endl;
using std::string;
using std::to_string;


#define LL_FATAL    "[FATAL]"
#define LL_ERROR    "[ERROR]"
#define LL_WARNING  "[WARN ]"
#define LL_INFO     "[INFO ]"
#define LL_DEBUG    "[DEBUG]"
#define LL_TRACE    "[TRACE]"


void my_log(const string str, string log_level = LL_INFO);
void my_sleep(const int milliseconds);
string my_pad_right(string const& str, const int length, const char c);
string my_pad_left(string const& str, const int length, const char c);


#endif // _HELPER_

test.cpp

/* 
COMPILE : gcc test.cpp mylib/helper.cpp -lstdc++ -o test
*/
#include <iostream>    // for using std, printf(),...
#include <string>      // for using std::string
#include <cstring>     // for using strcpy()
#include <unistd.h>    // for using fork()

#include "mylib/helper.h"

using std::cout;
using std::endl;
using std::string;
using std::to_string;

int main(int argc, char** argv) {
	my_log("Hello world");
	
	int pid;
	pid = fork();
	if(pid != 0)
	{
		while(1)
		{
			my_log("Parent process");
			my_sleep(1000);
		}
	}
	else
	{
		while(1)
		{
			my_log("Child process", LL_DEBUG);
			my_sleep(1000);
			// copy a into NULL pointer to simulate a coredump in order to produce a Zombie process
			strcpy("a", NULL);
		}		
	}
	
	return 0;
}

btnguyen@DESKTOP-UAIA29B:/mnt/h/DEVELOPER/Linux/prog$ ls -ltr
total 32
drwxrwxrwx 1 btnguyen btnguyen  4096 Aug 26 23:56 mylib
-rwxrwxrwx 1 btnguyen btnguyen 26768 Sep  3 22:02 test
-rwxrwxrwx 1 btnguyen btnguyen   710 Sep  3 22:06 test.cpp
btnguyen@DESKTOP-UAIA29B:/mnt/h/DEVELOPER/Linux/prog$ cd mylib
btnguyen@DESKTOP-UAIA29B:/mnt/h/DEVELOPER/Linux/prog/mylib$ ls -ltr
total 8
-rwxrwxrwx 1 btnguyen btnguyen  971 Aug 28 00:16 helper.h
-rwxrwxrwx 1 btnguyen btnguyen 1428 Sep  3 22:09 helper.cpp
btnguyen@DESKTOP-UAIA29B:/mnt/h/DEVELOPER/Linux/prog/mylib$