RAII.cpp

/******************************************************************************

Welcome to GDB Online.
GDB online is an online compiler and debugger tool for C, C++, Python, Java, PHP, Ruby, Perl,
C#, VB, Swift, Pascal, Fortran, Haskell, Objective-C, Assembly, HTML, CSS, JS, SQLite, Prolog.
Code, Compile, Run and Debug online from anywhere in world.

*******************************************************************************/
 #include <cstdio>
 #include <iostream>
 #include <exception>
 
 class BadFile: virtual public std::exception 
 {
  public:
    explicit BadFile(const std::string& msg):
        m_msg(msg)
    {}
    
    virtual ~BadFile() throw () {}

    virtual const char* what() const throw ()
    {
       return m_msg.c_str();
    }
        
  private:
    std::string m_msg;
 };
 
 
 class FileHandlerRAII
 {
  public:
    FileHandlerRAII(const char* fileName) : m_fp(std::fopen(fileName, "w+"))
    {
        if (m_fp == NULL) {
            throw BadFile(std::string(fileName) + " failed to be opened");
        }
        std::cout << "file resource: " << fileName << " acquired\n";
    }
    
    FileHandlerRAII(const FileHandlerRAII&)=delete; // no copy operations
    FileHandlerRAII& operator=(const FileHandlerRAII&)=delete;

    FileHandlerRAII(FileHandlerRAII&&)=delete; // no move operations
    FileHandlerRAII& operator=(FileHandlerRAII&&)=delete;
    
    bool write(const char* str)
    {
        if( std::fputs(str, m_fp) == EOF ) {
             return false ;
        }
        return true;
    }
    
    ~FileHandlerRAII()
    {
        if (m_fp != NULL) {
            std::fclose(m_fp) ;
            std::cout << "file resource released\n";
        }
    }
 private:
    FILE *m_fp;
};

int main()
{
    try {
        FileHandlerRAII raii("test.log");
        
        for (auto i = 0; i <3; i++) {
            if (raii.write("Hello RAII")) {
                std::cout << "file accessed successfully\n";
            }
            if (i == 1) {
                throw std::runtime_error("Bye bye cruel world !");
            }
        }
    }
    catch(...) {
        std::cout << "something went wrong \n";
    }
    
    return 0;
}