How to: Write text to a file

This topic shows different ways to write text to a file for a .NET app.

The following classes and methods are typically used to write text to a file:

StreamWriter contains methods to write to a file synchronously (Write and WriteLine) or asynchronously (WriteAsync and WriteLineAsync).

File provides static methods to write text to a file, such as WriteAllLines and WriteAllText, or to append text to a file, such as AppendAllLines, AppendAllText, and AppendText.

Path is for strings that have file or directory path information. It contains the Combine method and, in .NET Core 2.1 and later, the Join and TryJoin methods, which allow concatenation of strings to build a file or directory path.

The following examples show only the minimum amount of code needed. A real-world app usually provides more robust error checking and exception handling.

Example: Synchronously write text with StreamWriter

The following example shows how to use the StreamWriter class to synchronously write text to a new file one line at a time. Because the StreamWriter object is declared and instantiated in a using statement, the Dispose method is invoked, which automatically flushes and closes the stream.

If you would like to see code comments translated to languages other than English, let us know in this GitHub discussion issue.

Example: Synchronously append text with StreamWriter

The following example shows how to use the StreamWriter class to synchronously append text to the text file created in the first example.

Example: Asynchronously write text with StreamWriter

The following example shows how to asynchronously write text to a new file using the StreamWriter class. To invoke the WriteAsync method, the method call must be within an async method. The C# example requires C# 7.1 or later, which adds support for the async modifier on the program entry point.

Example: Write and append text with the File class

The following example shows how to write text to a new file and append new lines of text to the same file using the File class. The WriteAllText and AppendAllLines methods open and close the file automatically. If the path you provide to the WriteAllText method already exists, the file is overwritten.

How to append to a file with PowerShell

November 15, 2018 by Paulie 1 Comment

It’s easy to append text to a file with Windows Powershell with the Add-Content cmdlet, here are some examples:

1. Create a sample text file using notepad. I have created mine like this:
   
2. Open a Powershell Window and type:

If you open the text file again, you will see the text has been appended on to the end of the existing line:

The above example is fine, but as you can see the data was not written to a new line.

Example PowerShell to append text to a file on to a new line

To append content on to a new line you need to use the escape character followed by the letter “n”:

So to continue the example above you could use:

And then the resulting text file would look like this:

Append formatted data with Powershell by using tabs and new lines

This example creates a tab formatted file, the output looks like this:

The Powershell to create the above example is:

As you can see, the tabs are added with the special character “`t”.

Appending to a file using redirection

The process described above seems to be the “normal” way to append to a file in PowerShell. But if you have come from a Unix or Linux background that will probably seem like hard work compared to just using command redirection, which also works perfectly well in PowerShell. For example:

I don’t know why this method isn’t used more in PowerShell because it is much more succinct than “Add-Content”. Perhaps it is because it does not have the same level of functionality, in most cases it is fine.

Filed Under: How To Tagged With: Powershell

append append

Позволяет программам открывать файлы данных в указанных каталогах, как будто они находятся в текущем каталоге. Allows programs to open data files in specified directories as if they were in the current directory. При использовании без параметров append отображает список добавленных каталогов. If used without parameters, append displays the appended directory list.

Эта команда не поддерживается в Windows 10. This command not supported in Windows 10.

Синтаксис Syntax

Параметры Parameters

Параметр Parameter	Описание Description
[\ :]

Указывает диск и каталог для добавления. Specifies a drive and directory to append. /x: вкл. /x:on Применяет добавленные каталоги к поиску файлов и запуску приложений. Applies appended directories to file searches and launching applications. /x: Off /x:off Применяет добавленные каталоги только к запросам на открытие файлов. Applies appended directories only to requests to open files. Параметр /x: Off используется по умолчанию. The /x:off option is the default setting. /path: вкл. /path:on Применяет добавленные каталоги к запросам файлов, которые уже задают путь. Applies appended directories to file requests that already specify a path. /path: on — значение по умолчанию. /path:on is the default setting. /path: выкл. /path:off Отключает действие /path: on. Turns off the effect of /path:on. /e /e Сохраняет копию добавленного списка каталогов в переменной среды с именем APPEND. Stores a copy of the appended directory list in an environment variable named APPEND. параметр /e можно использовать только при первом использовании append после запуска системы. /e may be used only the first time you use append after starting your system. ; ; Очищает список добавленных каталогов. Clears the appended directory list. /? /? Отображение справки в командной строке. Displays help at the command prompt.

Примеры Examples

Чтобы очистить список добавленных каталогов, введите: To clear the appended directory list, type:

Чтобы сохранить копию присоединенного каталога в переменной среды с именем append, введите: To store a copy of the appended directory to an environment variable named append, type:

How to append data on a file in win32

I’ve searched to do this but I can’t find what am I doing incorrectly.I’m trying to make this function appends data every time it’s called but it always do it once. If the file doesn’t exist it creates a new one and write on file for ONLY once if the file exist it does nothing (or maybe overwrite)

And this is where I call the function in WM_COMMAND

1 Answer 1

if the file exist it does nothing

As it should be. Per the CreateFile() documentation:

CREATE_NEW
1
Creates a new file, only if it does not already exist.

If the specified file exists, the function fails and the last-error code is set to ERROR_FILE_EXISTS (80).

If the specified file does not exist and is a valid path to a writable location, a new file is created.

For what you are attempting to do, use OPEN_ALWAYS instead:

If the specified file exists, the function succeeds and the last-error code is set to ERROR_ALREADY_EXISTS (183).

If the specified file does not exist and is a valid path to a writable location, the function creates a file and the last-error code is set to zero.

You can use the FILE_APPEND_DATA access specifier to have CreateFile() automatically seek to the end of the file after creating/opening it (otherwise, you have to seek manually using SetFilePointer/Ex() ) before you then write new data to the file.

How do I append to a file using the COPY command

I’m running Windows 7 Ultimate x64, but my experience dates back to DOS 3.0.

Since like DOS 3.1 you’ve been able to append a file to another one with this use of the COPY command:

Making the need for a temporary FILE3 unnecessary.

It was a very convenient command since whenever you added a new program you often needed to update your CONFIG.SYS and AUTOEXEC.BAT files.

It also used to be that getting the order correct was importiant, otherwise you’d end up with an empty FILE1.

But today when I tried that, it left FILE1 untouched, and when I reversed the order, it (understandably) made FILE1 a copy of FILE2 .

Does anyone know if it’s been replaced with another method, and when this change happened?

EDIT:

I’ve been doing more testing, and oddly even though the above code won’t work, you still can sill copy from the console and append that to an existing file like this:

I’m wondering if my version of Windows is messed up somehow. Can any body replicate my findings?

EDIT:

It works on 95 / 98 / ME / 2000 / XP / XP Mode / 7 Professional x64 / 8 x64. So I imagine that it’s not a 7 Ultimate x64 problem, but rather an issue with my machine.

EDIT:

Last edit, I promise. 🙂

It was not an issue with my machine, it was an issue with File1. Apparently when I first appended File2 to it, the [CTRL]+Z (EOF character) never got overwritten, causing the file to look like this:

You can duplicate this yourself with the following experiment from at the command prompt. (Where ^Z is the character [CTRL]+Z )

At the command prompt type:

You can type file2 >> file1 or use nearly any other method of concatenating files, and when you type file1 it will still only appear to contain File One . BUT if you use FIND «searchterm» file to parse the file it will show you what’s REALLY going on. In this case type: