Write file cpp

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Must Learn Expand child menu Expand. In the previous example program, we showed you how to open a file and how to close the file. Now, we will show you how to write something in a file. We can write to a file using the stream insertion operator, i. In this program, we have used the file handler and insertion operator to write two lines in the file. Now, we will compile the above program and execute it. In the previous examples, we showed you how to write content to a file.

Once we compile and execute the program, it is clear that the output matches the content of the file. Therefore, we have successfully read the file and printed the content of the file to the monitor. The data is written to the current cursor position. The cursor position is updated after the write operation.

For more information about console handles, see CreateFile. When writing to a communications device, the behavior of WriteFile is determined by the current communication time-out as set and retrieved by using the SetCommTimeouts and GetCommTimeouts functions.

Unpredictable results can occur if you fail to set the time-out values. Although a single-sector write is atomic, a multi-sector write is not guaranteed to be atomic unless you are using a transaction that is, the handle created is a transacted handle; for example, a handle created using CreateFileTransacted. If you write directly to a volume that has a mounted file system, you must first obtain exclusive access to the volume. Otherwise, you risk causing data corruption or system instability, because your application's writes may conflict with other changes coming from the file system and leave the contents of the volume in an inconsistent state.

To prevent these problems, the following changes have been made in Windows Vista and later:. If the pipe buffer is full when an application uses the WriteFile function to write to a pipe, the write operation may not finish immediately. The write operation will be completed when a read operation using the ReadFile function makes more system buffer space available for the pipe.

For more information about pipes, see Pipes. File Management Functions. Another method to write to file is the built-in write function that can be called from the fstream object.

The write function takes a character string pointer and the size of the data stored at that address.