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C# Beyond Basics

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Writing Files

For writing text in a file we create a StreamWriter object with the path of the file, similar to how we create a StreamReader object.

Note

The platform currently doesn't support file writing so this can be practiced on a compiler on your PC.

The StreamWriter object offers a WriteLine method which can write text into a file. We will now try to write something to the text.txt file.

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var textFile = new StreamWriter("C:/Users/Admin/Desktop/text.txt");
textFile.WriteLine("This is some new text.");
textFile.WriteLine("This is the next line.");
textFile.WriteLine("Another line.");
textFile.Close();

              
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var textFile = new StreamWriter("C:/Users/Admin/Desktop/text.txt");
textFile.WriteLine("This is some new text.");
textFile.WriteLine("This is the next line.");
textFile.WriteLine("Another line.");
textFile.Close();

The above code will overwrite the previous content of the text.txt file and replace it with:

This is some new text.
This is the next line.
Another line.

StreamWriter has a second parameter called "append" which takes in a boolean value and is set to false by default. If we set the append parameter to true then the code will not overwrite the older text rather it would append the new text to the end of the file.

For-example, consider the file text.txt has the following text in it:

txt

text

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First line
Second line
Third line

              
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First line
Second line
Third line

We will use the following code to add a new line to it:

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using System;
using System.IO;

public class HelloWorld
{
public static void Main(string[] args)
{
var textFile = new StreamWriter("C:/Users/Admin/Desktop/text.txt", true);
textFile.WriteLine("This is a new line.");
textFile.Close();
}
}

              
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using System;
using System.IO;

public class HelloWorld
{
    public static void Main(string[] args)
    {
        var textFile = new StreamWriter("C:/Users/Admin/Desktop/text.txt", true);
        textFile.WriteLine("This is a new line.");
        textFile.Close();
    }
}

The file will look like this after running the code:

txt

text

copy
First line
Second line
Third line
This is a new line.

              
1234

            
First line
Second line
Third line
This is a new line.

1. What is the correct way of creating a StreamWriter object for appending text into a file?

2. What method is used to write a line to a text file using the StreamWriter class?

3. Which method is used for closing a file after use?

question mark

What is the correct way of creating a StreamWriter object for appending text into a file?

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question mark

What method is used to write a line to a text file using the StreamWriter class?

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question mark

Which method is used for closing a file after use?

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Seção 1. Capítulo 8
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