File.AppendAllLines Method

Reference

Definition

Namespace:: System.IO

Assemblies:: mscorlib.dll, System.IO.FileSystem.dll

Assembly:: System.IO.FileSystem.dll

Assembly:: System.Runtime.dll

Assembly:: mscorlib.dll

Assembly:: netstandard.dll

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

Appends lines to a file, and then closes the file.

Overloads

AppendAllLines(String, IEnumerable<String>)	Appends lines to a file, and then closes the file. If the specified file does not exist, this method creates a file, writes the specified lines to the file, and then closes the file.
AppendAllLines(String, IEnumerable<String>, Encoding)	Appends lines to a file by using a specified encoding, and then closes the file. If the specified file does not exist, this method creates a file, writes the specified lines to the file, and then closes the file.

AppendAllLines(String, IEnumerable<String>)

Source:: File.cs

Source:: File.cs

Source:: File.cs

Appends lines to a file, and then closes the file. If the specified file does not exist, this method creates a file, writes the specified lines to the file, and then closes the file.

public:
 static void AppendAllLines(System::String ^ path, System::Collections::Generic::IEnumerable<System::String ^> ^ contents);

public static void AppendAllLines (string path, System.Collections.Generic.IEnumerable<string> contents);

static member AppendAllLines : string * seq<string> -> unit

Public Shared Sub AppendAllLines (path As String, contents As IEnumerable(Of String))

Parameters

path: String

The file to append the lines to. The file is created if it doesn't already exist.

contents: IEnumerable<String>

The lines to append to the file.

Exceptions

ArgumentException

path is a zero-length string, contains only white space, or contains one more invalid characters defined by the GetInvalidPathChars() method.

ArgumentNullException

Either path or contents is null.

DirectoryNotFoundException

path is invalid (for example, the directory doesn't exist or it is on an unmapped drive).

FileNotFoundException

The file specified by path was not found.

IOException

An I/O error occurred while opening the file.

PathTooLongException

path exceeds the system-defined maximum length.

NotSupportedException

path is in an invalid format.

SecurityException

The caller does not have permission to write to the file.

UnauthorizedAccessException

path specifies a file that is read-only.

-or-

This operation is not supported on the current platform.

-or-

path is a directory.

Examples

The following example writes selected lines from a sample data file to a file, and then appends more lines. The directory named temp on drive C must exist for the example to complete successfully.

using System;
using System.IO;
using System.Linq;

class Program
{
    static string dataPath = @"c:\temp\timestamps.txt";

    static void Main(string[] args)
    {
        CreateSampleFile();

        var JulyWeekends = from line in File.ReadLines(dataPath)
                           where (line.StartsWith("Saturday") ||
                           line.StartsWith("Sunday")) &
                           line.Contains("July")
                           select line;

        File.WriteAllLines(@"C:\temp\selectedDays.txt", JulyWeekends);

        var MarchMondays = from line in File.ReadLines(dataPath)
                           where line.StartsWith("Monday") &&
                           line.Contains("March")
                           select line;

        File.AppendAllLines(@"C:\temp\selectedDays.txt", MarchMondays);
    }

    static void CreateSampleFile()
    {
        DateTime TimeStamp = new DateTime(1700, 1, 1);

        using (StreamWriter sw = new StreamWriter(dataPath))
        {
            for (int i = 0; i < 500; i++)
            {
                DateTime TS1 = TimeStamp.AddYears(i);
                DateTime TS2 = TS1.AddMonths(i);
                DateTime TS3 = TS2.AddDays(i);
                sw.WriteLine(TS3.ToLongDateString());
            }
        }
    }
}

open System
open System.IO

let dataPath = @"c:\temp\timestamps.txt"

let createSampleFile () =
    let timeStamp = DateTime(1700, 1, 1)

    use sw = new StreamWriter(dataPath)

    for i = 0 to 499 do
        let ts1 = timeStamp.AddYears i
        let ts2 = ts1.AddMonths i
        let ts3 = ts2.AddDays i
        ts3.ToLongDateString() |> sw.WriteLine

createSampleFile ()

let julyWeekends =
    File.ReadLines dataPath
    |> Seq.filter (fun line ->
        (line.StartsWith "Saturday"
         || line.StartsWith "Sunday")
        && line.Contains "July")

File.WriteAllLines(@"C:\temp\selectedDays.txt", julyWeekends)

let marchMondays =
    File.ReadLines dataPath
    |> Seq.filter (fun line -> line.StartsWith "Monday" && line.Contains "March")

File.AppendAllLines(@"C:\temp\selectedDays.txt", marchMondays)

Imports System.IO
Imports System.Linq

Class Program
    Shared dataPath As String = "c:\temp\timestamps.txt"

    Public Shared Sub Main(ByVal args As String())
        CreateSampleFile()

        Dim JulyWeekends = From line In File.ReadLines(dataPath) _
            Where (line.StartsWith("Saturday") OrElse _
            line.StartsWith("Sunday")) And line.Contains("July") _
            Select line

        File.WriteAllLines("C:\temp\selectedDays.txt", JulyWeekends)

        Dim MarchMondays = From line In File.ReadLines(dataPath) _
            Where line.StartsWith("Monday") AndAlso line.Contains("March") _
            Select line

        File.AppendAllLines("C:\temp\selectedDays.txt", MarchMondays)
    End Sub

    Private Shared Sub CreateSampleFile()
        Dim TimeStamp As New DateTime(1700, 1, 1)

        Using sw As New StreamWriter(dataPath)
            For i As Integer = 0 To 499
                Dim TS1 As DateTime = TimeStamp.AddYears(i)
                Dim TS2 As DateTime = TS1.AddMonths(i)
                Dim TS3 As DateTime = TS2.AddDays(i)

                sw.WriteLine(TS3.ToLongDateString())
            Next
        End Using
    End Sub
End Class

Remarks

The method creates the file if it doesn't exist, but it doesn't create new directories. Therefore, the value of the path parameter must contain existing directories.

Applies to

AppendAllLines(String, IEnumerable<String>, Encoding)

Source:: File.cs

Source:: File.cs

Source:: File.cs

Appends lines to a file by using a specified encoding, and then closes the file. If the specified file does not exist, this method creates a file, writes the specified lines to the file, and then closes the file.

public:
 static void AppendAllLines(System::String ^ path, System::Collections::Generic::IEnumerable<System::String ^> ^ contents, System::Text::Encoding ^ encoding);

public static void AppendAllLines (string path, System.Collections.Generic.IEnumerable<string> contents, System.Text.Encoding encoding);

static member AppendAllLines : string * seq<string> * System.Text.Encoding -> unit

Public Shared Sub AppendAllLines (path As String, contents As IEnumerable(Of String), encoding As Encoding)

Parameters

path: String

The file to append the lines to. The file is created if it doesn't already exist.

contents: IEnumerable<String>

The lines to append to the file.

encoding: Encoding

The character encoding to use.

Exceptions

ArgumentException

path is a zero-length string, contains only white space, or contains one more invalid characters defined by the GetInvalidPathChars() method.

ArgumentNullException

Either path, contents, or encoding is null.

DirectoryNotFoundException

path is invalid (for example, the directory doesn't exist or it is on an unmapped drive).

FileNotFoundException

The file specified by path was not found.

IOException

An I/O error occurred while opening the file.

PathTooLongException

path exceeds the system-defined maximum length.

NotSupportedException

path is in an invalid format.

SecurityException

The caller does not have the required permission.

UnauthorizedAccessException

path specifies a file that is read-only.

-or-

This operation is not supported on the current platform.

-or-

path is a directory.

-or-

The caller does not have the required permission.

Remarks

The method creates the file if it doesn't exist, but it doesn't create new directories. Therefore, the value of the path parameter must contain existing directories.

You can use this method to create a file that contains the following:

The results of a LINQ to Objects query on the lines of a file, as obtained by using the ReadLines method.
The contents of a collection that implements an IEnumerable<T> of strings.

Applies to

Share via

File.AppendAllLines Method

Definition

Overloads

AppendAllLines(String, IEnumerable<String>)

Parameters

Exceptions

Examples

Remarks

Applies to

AppendAllLines(String, IEnumerable<String>, Encoding)

Parameters

Exceptions

Remarks

Applies to

Additional resources