Subsequent data written to the file is always appended to the end of file. (Because the or’ingreturns an int, open() takes an int rather than an open_mode argument.) The meanings of these bits in mode are:Ī seek to the end of file is performed. The members of open_mode are bits that may be or’ed together. ![]() "(INCORE)" for a temporary binary file that is only set up in virtual memoryįor more detailed information, please refer to the "C Library Functions" manual."(SYSDTA)", "(SYSOUT)", "(SYSLST)" for the appropriate system file."link= linkname", where linkname is a BS2000 link name. ![]() ios::failbit is set in f’s error status on failure. Failure occurs if f is already open, or the C runtime system call open() fails. If the file does not already exist, an attempt is made to create it unless ios::nocreate or ios::in is set. Void f.open(char * name, int mode, int prot) f’serror state is cleared except on failure, which is when the C runtime system detects afailure in the system call close(). A failure sets ios::failbit in f’s error state.Ĭloses any associated filebuf and thereby breaks the connection of the f to a file. A failure occurs when f is already connected to afile. Member functionsĬonnects f to the file descriptor fd. If ptr is NULL or len is 0, the filebuf is unbuffered. The error state (io_state) of the constructed xstream indicates failure in case the open fails.Ĭonstructs an xstream connected to file descriptor fd, which must be already open.Ĭonstructs an xstream connected to file descriptor fd, and, in addition, initializes theĪssociated filebuf to use the len bytes at ptr as the reserve area. For a description of parameters name and mode, see under open() below. mode is an int representing an open_mode.Ĭonstructs an xstream and opens file name using mode as the open mode.f is any of ifstream, ofstream, or fstream.In the following descriptions, assume that: That is, the associated streambuf is a filebuf. Ifstream, ofstream, and fstream specialize istream, ostream, and iostream, respectively, to files. ![]() But suddenly, it fails to compile, because apparently, when supplied a custom deleter, the unique_ptr becomes a different type.Open(const char* name, int mode, int prot=filebuf::openprot) īase class fstreambase contains the standard definitions for constructors and memberfunctions for derived classes. So I have to supply a custom deleter (that does nothing) for the cin case. This works for ifstream but not for cin, because you can't delete cin. At first, I tried unique_ptr open_for_read(const string& filename) So I figure, the modern C++ way would be to use smart pointers with streams. It works, and it's safe to fclose(stdin) later on (in case one doesn't forget to), but then I would lose access to the stream methods such as std::getline. I first considered the old-school FILE*: FILE *open_for_read(const char *filename)
0 Comments
Leave a Reply. |