Writing text files in C Sharp (C#) - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to write a line of text to a file.

C Sharp (C#)

using System.IO;

File.WriteAllText("example.txt", [1]);

Drag options to blanks, or click blank then click option'

AFile.Write

BHello, world!

CWriteLine

D"Hello, world!"

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to put the text inside quotes.

Using a method name instead of the text string.

The WriteAllText method requires a string as the second argument, so the text must be in quotes.

2fill in blank

medium

Complete the code to append a line to an existing file.

C Sharp (C#)

using System.IO;

File.[1]("example.txt", "New line");

Drag options to blanks, or click blank then click option'

AAppendAllText

BWriteAllText

CWriteLine

DWriteText

Attempts:

3 left

💡 Hint

Common Mistakes

Using WriteAllText which overwrites the file.

Using a non-existent method like WriteLine.

AppendAllText adds text to the end of the file without overwriting it.

3fill in blank

hard

Fix the error in the code to write multiple lines to a file.

C Sharp (C#)

using System.IO;

string[] lines = {"First line", "Second line"};
File.WriteAllText("example.txt", [1]);

Drag options to blanks, or click blank then click option'

Astring.Join("\n", lines)

Blines

Clines.ToString()

Dlines[0]

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the array directly which causes an error.

Using ToString() on the array which returns the type name.

WriteAllText expects a single string, so we join the array elements with newlines.

4fill in blank

hard

Fill both blanks to write lines to a file using a StreamWriter.

C Sharp (C#)

using System.IO;

using (StreamWriter writer = new StreamWriter("example.txt", [1]))
{
    writer.[2]("Hello");
}

Drag options to blanks, or click blank then click option'

Atrue

Bfalse

CWriteLine

DWrite

Attempts:

3 left

💡 Hint

Common Mistakes

Using false for append which overwrites the file.

Using Write which does not add a newline.

The first blank is true to append to the file, and WriteLine writes a line with a newline.

5fill in blank

hard

Fill all three blanks to write multiple lines using StreamWriter in a loop.

C Sharp (C#)

using System.IO;

string[] lines = {"One", "Two", "Three"};
using (StreamWriter writer = new StreamWriter("example.txt", [1]))
{
    foreach (string [2] in lines)
    {
        writer.[3]([2]);
    }
}

Drag options to blanks, or click blank then click option'

Afalse

Bline

CWriteLine

Dtrue

Attempts:

3 left

💡 Hint

Common Mistakes

Setting append to false which erases the file.

Using an undefined variable name in the loop.

Using Write instead of WriteLine.

We append to the file (true), use 'line' as the loop variable, and WriteLine to write each line.