C ++ fstream错误未知

Question

I'm trying to make a wrapper for a file - so a small wrapper to fstream. I am in the process of making something that will want to read/write binary and text to file, so I can make model loaders talk in the same way.

I've one question: Why doesn't my file open when I call with this in ObjLoader.cpp ?

Scatterbrain::Log *_file = new Scatterbrain::Log( path, false, true );

    if( ! _file->Works() )
        std::cout << "Error!!";

Having this in scatterbrain.h ? I'm sure I've included the necessary headers as everything compiles fine, so I figure it must be a semantic problem with the way I wrote the file open call? - it is getting called..

namespace Scatterbrain
{
    class Log
    {
        private:
            std::string name;
            bool rOnly;
            bool isBinary;
            int numBytes;
            std::fstream file;
        protected:  
            virtual int SizeBytes() { numBytes = (file) ? (int) file->tellg() : 0; return numBytes; }
        public: 
            Log(){}     
            Log( std::string filename, bool append, bool readOnly )
            {
                if(FileExists(filename))
                {
                    name = filename;
                    rOnly = readOnly;
                    file.open( name.c_str(), ((readOnly) ?  int(std::ios::out) : int(std::ios::in |std::ios::out)) | ((append) ? int(std::ios::app) : int(std::ios::trunc)) );
                }
            }
            virtual bool Works() { return (file.is_open() && file.good() ); }

Thanks

Answer 1

There's a lot that could be said about this all, so I'll just put it in comments:

class Log
{
private:
    std::string name;
    bool rOnly;
    std::fstream file;

public:
    Log(){}

    Log( std::string filename, bool append, bool readOnly)
        : name(filename), // Use initializer lists
          rOnly(readOnly),
          file(filename, (readOnly ?  std::ios::out : std::ios::in | std::ios::out) |
               (append ? std::ios::app : std::ios::trunc))
    {
        // Why check if the file exists? Just try to open it...
        // Unless, of course, you want to prevent people from creating
        // new log files.
    }

    virtual bool Works()
    {
        // Just use the fstream's operator bool() to check if it's good
        return file;
    }
};

In short:

1. Use member initializer lists
2. Don't use new ... I have no idea why you were in the first place, or why it compiled if it did.
3. Use the operator bool() function to see if it's "good" or not.