File.AppendAllLines Method
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Appends lines to a file, and then closes the file.
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. |
- 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
path
is a zero-length string, contains only white space, or contains one more invalid characters defined by the GetInvalidPathChars() method.
Either path
or contents
is null
.
path
is invalid (for example, the directory doesn't exist or it is on an unmapped drive).
The file specified by path
was not found.
An I/O error occurred while opening the file.
path
exceeds the system-defined maximum length.
path
is in an invalid format.
The caller does not have permission to write to the file.
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
.NET 9 and other versions
Product | Versions |
---|---|
.NET | Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Framework | 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
.NET Standard | 1.3, 1.4, 1.6, 2.0, 2.1 |
UWP | 10.0 |
- 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
path
is a zero-length string, contains only white space, or contains one more invalid characters defined by the GetInvalidPathChars() method.
Either path
, contents
, or encoding
is null
.
path
is invalid (for example, the directory doesn't exist or it is on an unmapped drive).
The file specified by path
was not found.
An I/O error occurred while opening the file.
path
exceeds the system-defined maximum length.
path
is in an invalid format.
The caller does not have the required permission.
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
.NET 9 and other versions
Product | Versions |
---|---|
.NET | Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Framework | 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
.NET Standard | 1.3, 1.4, 1.6, 2.0, 2.1 |
UWP | 10.0 |
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