File.WriteAllLines Method
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Creates a new file, writes one or more strings to the file, and then closes the file.
WriteAllLines(String, String[], Encoding) |
Creates a new file, writes the specified string array to the file by using the specified encoding, and then closes the file. |
WriteAllLines(String, IEnumerable<String>, Encoding) |
Creates a new file by using the specified encoding, writes a collection of strings to the file, and then closes the file. |
WriteAllLines(String, IEnumerable<String>) |
Creates a new file, writes a collection of strings to the file, and then closes the file. |
WriteAllLines(String, String[]) |
Creates a new file, write the specified string array to the file, and then closes the file. |
- Source:
- File.cs
- Source:
- File.cs
- Source:
- File.cs
Creates a new file, writes the specified string array to the file by using the specified encoding, and then closes the file.
public:
static void WriteAllLines(System::String ^ path, cli::array <System::String ^> ^ contents, System::Text::Encoding ^ encoding);
public static void WriteAllLines (string path, string[] contents, System.Text.Encoding encoding);
static member WriteAllLines : string * string[] * System.Text.Encoding -> unit
Public Shared Sub WriteAllLines (path As String, contents As String(), encoding As Encoding)
Parameters
- path
- String
The file to write to.
- contents
- String[]
The string array to write to the file.
- encoding
- Encoding
An Encoding object that represents the character encoding applied to the string array.
Exceptions
.NET Framework and .NET Core versions older than 2.1: path
is a zero-length string, contains only white space, or contains one or more invalid characters. You can query for invalid characters by using the GetInvalidPathChars() method.
Either path
or contents
is null
.
The specified path, file name, or both exceed the system-defined maximum length.
The specified path is invalid (for example, it is on an unmapped drive).
An I/O error occurred while opening the file.
path
specified a file that is read-only.
-or-
path
specified a file that is hidden.
-or-
This operation is not supported on the current platform.
-or-
path
specified a directory.
-or-
The caller does not have the required permission.
path
is in an invalid format.
The caller does not have the required permission.
Examples
The following code example demonstrates the use of the WriteAllLines method to write text to a file. In this example a file is created, if it doesn't already exist, and text is added to it.
using System;
using System.IO;
using System.Text;
class Test
{
public static void Main()
{
string path = @"c:\temp\MyTest.txt";
// This text is added only once to the file.
if (!File.Exists(path))
{
// Create a file to write to.
string[] createText = { "Hello", "And", "Welcome" };
File.WriteAllLines(path, createText, Encoding.UTF8);
}
// This text is always added, making the file longer over time
// if it is not deleted.
string appendText = "This is extra text" + Environment.NewLine;
File.AppendAllText(path, appendText, Encoding.UTF8);
// Open the file to read from.
string[] readText = File.ReadAllLines(path, Encoding.UTF8);
foreach (string s in readText)
{
Console.WriteLine(s);
}
}
}
open System
open System.IO
open System.Text
let path = @"c:\temp\MyTest.txt"
// This text is added only once to the file.
if File.Exists path |> not then
// Create a file to write to.
let createText = [ "Hello"; "And"; "Welcome" ]
File.WriteAllLines(path, createText, Encoding.UTF8)
// This text is always added, making the file longer over time
// if it is not deleted.
let appendText =
"This is extra text" + Environment.NewLine
File.AppendAllText(path, appendText, Encoding.UTF8)
// Open the file to read from.
let readText = File.ReadAllLines(path, Encoding.UTF8)
for s in readText do
printfn $"{s}"
Imports System.IO
Imports System.Text
Public Class Test
Public Shared Sub Main()
Dim path As String = "c:\temp\MyTest.txt"
Dim sw As StreamWriter
' This text is added only once to the file.
If File.Exists(path) = False Then
' Create a file to write to.
Dim createText() As String = {"Hello", "And", "Welcome"}
File.WriteAllLines(path, createText, Encoding.UTF8)
End If
' This text is always added, making the file longer over time
' if it is not deleted.
Dim appendText As String = "This is extra text" + Environment.NewLine
File.AppendAllText(path, appendText, Encoding.UTF8)
' Open the file to read from.
Dim readText() As String = File.ReadAllLines(path, Encoding.UTF8)
Dim s As String
For Each s In readText
Console.WriteLine(s)
Next
End Sub
End Class
Remarks
If the target file already exists, it is truncated and overwritten.
Given a string array and a file path, this method opens the specified file, writes the string array to the file using the specified encoding, and then closes the file.
Applies to
.NET 9 and other versions
Product | Versions |
---|---|
.NET | Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Framework | 2.0, 3.0, 3.5, 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 | 2.0, 2.1 |
- Source:
- File.cs
- Source:
- File.cs
- Source:
- File.cs
Creates a new file by using the specified encoding, writes a collection of strings to the file, and then closes the file.
public:
static void WriteAllLines(System::String ^ path, System::Collections::Generic::IEnumerable<System::String ^> ^ contents, System::Text::Encoding ^ encoding);
public static void WriteAllLines (string path, System.Collections.Generic.IEnumerable<string> contents, System.Text.Encoding encoding);
static member WriteAllLines : string * seq<string> * System.Text.Encoding -> unit
Public Shared Sub WriteAllLines (path As String, contents As IEnumerable(Of String), encoding As Encoding)
Parameters
- path
- String
The file to write to.
- contents
- IEnumerable<String>
The lines to write to the file.
- encoding
- Encoding
The character encoding to use.
Exceptions
.NET Framework and .NET Core versions older than 2.1: path
is a zero-length string, contains only white space, or contains one or more invalid characters defined by the GetInvalidPathChars() method.
Either path
, contents
, or encoding
is null
.
path
is invalid (for example, it is on an unmapped drive).
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
specified a file that is read-only.
-or-
path
specified a file that is hidden.
-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
If the target file already exists, it is truncated and overwritten.
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 |
- Source:
- File.cs
- Source:
- File.cs
- Source:
- File.cs
Creates a new file, writes a collection of strings to the file, and then closes the file.
public:
static void WriteAllLines(System::String ^ path, System::Collections::Generic::IEnumerable<System::String ^> ^ contents);
public static void WriteAllLines (string path, System.Collections.Generic.IEnumerable<string> contents);
static member WriteAllLines : string * seq<string> -> unit
Public Shared Sub WriteAllLines (path As String, contents As IEnumerable(Of String))
Parameters
- path
- String
The file to write to.
- contents
- IEnumerable<String>
The lines to write to the file.
Exceptions
.NET Framework and .NET Core versions older than 2.1: path
is a zero-length string, contains only white space, or contains one or more invalid characters defined by the GetInvalidPathChars() method.
Either path
or contents
is null
.
path
is invalid (for example, it is on an unmapped drive).
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
specified a file that is read-only.
-or-
path
specified a file that is hidden.
-or-
This operation is not supported on the current platform.
-or-
path
is a directory.
-or-
The caller does not have the required permission.
Examples
The following example writes selected lines from a sample data file to a file.
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 default behavior of the WriteAllLines(String, IEnumerable<String>) method is to write out data by using UTF-8 encoding without a byte order mark (BOM). If it is necessary to include a UTF-8 identifier, such as a byte order mark, at the beginning of a file, use the WriteAllLines(String, IEnumerable<String>, Encoding) method overload with UTF8 encoding.
If the target file already exists, it is truncated and overwritten.
You can use this method to create the contents for a collection class that takes an IEnumerable<T> in its constructor, such as a List<T>, HashSet<T>, or a SortedSet<T> class.
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
Creates a new file, write the specified string array to the file, and then closes the file.
public:
static void WriteAllLines(System::String ^ path, cli::array <System::String ^> ^ contents);
public static void WriteAllLines (string path, string[] contents);
static member WriteAllLines : string * string[] -> unit
Public Shared Sub WriteAllLines (path As String, contents As String())
Parameters
- path
- String
The file to write to.
- contents
- String[]
The string array to write to the file.
Exceptions
.NET Framework and .NET Core versions older than 2.1: path
is a zero-length string, contains only white space, or contains one or more invalid characters. You can query for invalid characters by using the GetInvalidPathChars() method.
Either path
or contents
is null
.
The specified path, file name, or both exceed the system-defined maximum length.
The specified path is invalid (for example, it is on an unmapped drive).
An I/O error occurred while opening the file.
path
specified a file that is read-only.
-or-
path
specified a file that is hidden.
-or-
This operation is not supported on the current platform.
-or-
path
specified a directory.
-or-
The caller does not have the required permission.
path
is in an invalid format.
The caller does not have the required permission.
Examples
The following code example demonstrates the use of the WriteAllLines method to write text to a file. In this example a file is created, if it doesn't already exist, and text is added to it.
using System;
using System.IO;
class Test
{
public static void Main()
{
string path = @"c:\temp\MyTest.txt";
// This text is added only once to the file.
if (!File.Exists(path))
{
// Create a file to write to.
string[] createText = { "Hello", "And", "Welcome" };
File.WriteAllLines(path, createText);
}
// This text is always added, making the file longer over time
// if it is not deleted.
string appendText = "This is extra text" + Environment.NewLine;
File.AppendAllText(path, appendText);
// Open the file to read from.
string[] readText = File.ReadAllLines(path);
foreach (string s in readText)
{
Console.WriteLine(s);
}
}
}
open System
open System.IO
let path = @"c:\temp\MyTest.txt"
// This text is added only once to the file.
if File.Exists path |> not then
// Create a file to write to.
let createText = [ "Hello"; "And"; "Welcome" ]
File.WriteAllLines(path, createText)
// This text is always added, making the file longer over time
// if it is not deleted.
let appendText =
"This is extra text" + Environment.NewLine
File.AppendAllText(path, appendText)
// Open the file to read from.
let readText = File.ReadAllLines path
for s in readText do
printfn $"{s}"
Imports System.IO
Public Class Test
Public Shared Sub Main()
Dim path As String = "c:\temp\MyTest.txt"
Dim sw As StreamWriter
' This text is added only once to the file.
If File.Exists(path) = False Then
' Create a file to write to.
Dim createText() As String = {"Hello", "And", "Welcome"}
File.WriteAllLines(path, createText)
End If
' This text is always added, making the file longer over time
' if it is not deleted.
Dim appendText As String = "This is extra text" + Environment.NewLine
File.AppendAllText(path, appendText)
' Open the file to read from.
Dim readText() As String = File.ReadAllLines(path)
Dim s As String
For Each s In readText
Console.WriteLine(s)
Next
End Sub
End Class
Remarks
If the target file already exists, it is truncated and overwritten.
The default behavior of the WriteAllLines method is to write out data using UTF-8 encoding without a byte order mark (BOM). If it is necessary to include a UTF-8 identifier, such as a byte order mark, at the beginning of a file, use the WriteAllLines(String, String[], Encoding) method overload with UTF8 encoding.
Given a string array and a file path, this method opens the specified file, writes the string array to the file, and then closes the file.
Applies to
.NET 9 and other versions
Product | Versions |
---|---|
.NET | Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Framework | 2.0, 3.0, 3.5, 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 | 2.0, 2.1 |
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