open_write()

std::ofstream xtd::io::file_info::open_write

(

)

const

Creates a write-only std::ofstream.

Returns

A write-only unshared std::ofstream object for a new or existing file.

Exceptions

xtd::unauthorized_access_exception	The path specified when creating an instance of the xtd::io::file_info object is read-only or is a directory.
xtd::io::directory_not_found_exception	The path specified when creating an instance of the xtd::io::file_info object is invalid, such as being on an unmapped drive.

Examples

The following example opens a file for writing and then reads from the file.

#include <xtd/io/file_info>
#include <xtd/io/stream_reader>
#include <xtd/io/stream_writer>
#include <xtd/block_scope>
#include <xtd/console>
#include <xtd/startup>
 
using namespace xtd;
using namespace xtd::io;
 
class program {
public:
  static auto main() {
    auto path = "MyTest.txt";
    auto fi = file_info {path};
    
    // Delete the file if it exists.
    if (fi.exists())
      fi.remove();
      
    //Create the file.
    block_scope_(auto fs = fi.create()) {
      auto sw = stream_writer {fs};
      sw.write_line("This is some text in the file.");
    }
    
    //Open the stream and read it back.
    block_scope_(auto fs = fi.open(std::ios::in)) {
      auto sr = stream_reader {fs};
      while (!sr.end_of_stream())
        console::write_line(sr.read_line());
    }
  }
};
 
startup_(program::main);
 
// This code produces the following output :
//
// This is some text in the file.

Returns

The xtd::io::file_info::open_write method opens a file if one already exists for the file path, or creates a new file if one does not exist. For an existing file, it does not append the new text to the existing text. Instead, it overwrites the existing characters with the new characters. If you overwrite a longer string (such as "This is a test of the open_write method") with a shorter string (like "Second run"), the file will contain a mix of the strings ("Second runtest of the open_write method").