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Como: Gravar texto em um arquivo

Este artigo mostra diferentes maneiras de escrever texto em um arquivo para um aplicativo .NET.

As seguintes classes e métodos são normalmente usados para gravar texto em um arquivo:

Nota

Os exemplos a seguir mostram apenas a quantidade mínima de código necessária. Um aplicativo do mundo real geralmente fornece verificação de erros mais robusta e tratamento de exceções.

Exemplo: escrever texto de forma síncrona com o StreamWriter

O exemplo a seguir mostra como usar a classe para gravar texto de forma síncrona StreamWriter em um novo arquivo, uma linha de cada vez. Como o objeto é declarado StreamWriter e instanciado em uma using instrução, o método é invocado, o Dispose que libera e fecha automaticamente o fluxo.

using System;
using System.IO;

class Program
{
    static void Main(string[] args)
    {

        // Create a string array with the lines of text
        string[] lines = { "First line", "Second line", "Third line" };

        // Set a variable to the Documents path.
        string docPath =
          Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);

        // Write the string array to a new file named "WriteLines.txt".
        using (StreamWriter outputFile = new StreamWriter(Path.Combine(docPath, "WriteLines.txt")))
        {
            foreach (string line in lines)
                outputFile.WriteLine(line);
        }
    }
}
// The example creates a file named "WriteLines.txt" with the following contents:
// First line
// Second line
// Third line
Imports System.IO

Class WriteText

    Public Shared Sub Main()

        ' Create a string array with the lines of text
        Dim lines() As String = {"First line", "Second line", "Third line"}

        ' Set a variable to the Documents path.
        Dim docPath As String = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments)

        ' Write the string array to a new file named "WriteLines.txt".
        Using outputFile As New StreamWriter(Path.Combine(docPath, Convert.ToString("WriteLines.txt")))
            For Each line As String In lines
                outputFile.WriteLine(line)
            Next
        End Using

    End Sub

End Class

' The example creates a file named "WriteLines.txt" with the following contents:
' First line
' Second line
' Third line

Exemplo: acrescentar texto de forma síncrona com o StreamWriter

O exemplo a seguir mostra como usar a StreamWriter classe para acrescentar texto de forma síncrona ao arquivo de texto criado no primeiro exemplo:

using System;
using System.IO;

class Program
{
    static void Main(string[] args)
    {

        // Set a variable to the Documents path.
        string docPath = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);

        // Append text to an existing file named "WriteLines.txt".
        using (StreamWriter outputFile = new StreamWriter(Path.Combine(docPath, "WriteLines.txt"), true))
        {
            outputFile.WriteLine("Fourth Line");
        }
    }
}
// The example adds the following line to the contents of "WriteLines.txt":
// Fourth Line
Imports System.IO

Class AppendText

    Public Shared Sub Main()

        ' Set a variable to the Documents path.
        Dim docPath As String =
            Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments)

        ' Append text to an existing file named "WriteLines.txt".
        Using outputFile As New StreamWriter(Path.Combine(docPath, Convert.ToString("WriteLines.txt")), True)
            outputFile.WriteLine("Fourth Line")
        End Using

    End Sub

End Class

' The example adds the following line to the contents of "WriteLines.txt":
' Fourth Line

Exemplo: escrever texto de forma assíncrona com o StreamWriter

O exemplo a seguir mostra como gravar texto de forma assíncrona em um novo arquivo usando a StreamWriter classe. Para invocar o WriteAsync método, a chamada de método deve estar dentro de um async método.

using System;
using System.IO;
using System.Threading.Tasks;

class Program
{
    static async Task Main()
    {
        // Set a variable to the Documents path.
        string docPath = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);

        // Write the specified text asynchronously to a new file named "WriteTextAsync.txt".
        using (StreamWriter outputFile = new StreamWriter(Path.Combine(docPath, "WriteTextAsync.txt")))
        {
            await outputFile.WriteAsync("This is a sentence.");
        }
    }
}
// The example creates a file named "WriteTextAsync.txt" with the following contents:
// This is a sentence.
Imports System.IO

Public Module Example
    Public Sub Main()
        WriteTextAsync()
    End Sub

    Async Sub WriteTextAsync()
        ' Set a variable to the Documents path.
        Dim docPath As String = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments)

        ' Write the text asynchronously to a new file named "WriteTextAsync.txt".
        Using outputFile As New StreamWriter(Path.Combine(docPath, Convert.ToString("WriteTextAsync.txt")))
            Await outputFile.WriteAsync("This is a sentence.")
        End Using
    End Sub
End Module

' The example creates a file named "WriteTextAsync.txt" with the following contents:
' This is a sentence.

Exemplo: Escrever e acrescentar texto com a classe File

O exemplo a seguir mostra como gravar texto em um novo arquivo e acrescentar novas linhas de texto ao mesmo arquivo usando a File classe. Os WriteAllText métodos e AppendAllLines abrem e fecham o arquivo automaticamente. Se o caminho fornecido para o WriteAllText método já existir, o arquivo será substituído.

using System;
using System.IO;

class Program
{
    static void Main(string[] args)
    {
        // Create a string with a line of text.
        string text = "First line" + Environment.NewLine;

        // Set a variable to the Documents path.
        string docPath = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);

        // Write the text to a new file named "WriteFile.txt".
        File.WriteAllText(Path.Combine(docPath, "WriteFile.txt"), text);

        // Create a string array with the additional lines of text
        string[] lines = { "New line 1", "New line 2" };

        // Append new lines of text to the file
        File.AppendAllLines(Path.Combine(docPath, "WriteFile.txt"), lines);
    }
}
// The example creates a file named "WriteFile.txt" with the contents:
// First line
// And then appends the following contents:
// New line 1
// New line 2
Imports System.IO

Class WriteFile

    Public Shared Sub Main()

        ' Create a string array with the lines of text
        Dim text As String = "First line" & Environment.NewLine

        ' Set a variable to the Documents path.
        Dim docPath As String = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments)

        ' Write the text to a new file named "WriteFile.txt".
        File.WriteAllText(Path.Combine(docPath, Convert.ToString("WriteFile.txt")), text)

        ' Create a string array with the additional lines of text
        Dim lines() As String = {"New line 1", "New line 2"}

        ' Append new lines of text to the file
        File.AppendAllLines(Path.Combine(docPath, Convert.ToString("WriteFile.txt")), lines)

    End Sub

End Class

' The example creates a file named "WriteFile.txt" with the following contents:
' First line
' And then appends the following contents:
' New line 1
' New line 2

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