Why file operations matter in C Sharp (C#) - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to open a file for reading.

C Sharp (C#)

using System.IO;

var file = new StreamReader([1]);

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

AStreamReader

Bdata.txt

CFile.OpenRead

D"data.txt"

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to put the file name in quotes.

Using a method name instead of a file name.

The file name must be a string in quotes to open it correctly.

2fill in blank

medium

Complete the code to write text to a file.

C Sharp (C#)

using System.IO;

using var writer = new StreamWriter([1]);
writer.WriteLine("Hello World");

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

A"output.txt"

BConsole.Out

CFile.ReadAllText

DStreamReader

Attempts:

3 left

💡 Hint

Common Mistakes

Using reading methods instead of writing.

Not using quotes around the file name.

To write to a file, provide the file name as a string to StreamWriter.

3fill in blank

hard

Fix the error in the code to read all lines from a file.

C Sharp (C#)

string[] lines = File.[1]("log.txt");

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

AReadAllLines

BWriteAllLines

CWriteAllText

DOpenWrite

Attempts:

3 left

💡 Hint

Common Mistakes

Using write methods instead of read methods.

Confusing ReadAllText with ReadAllLines.

Use ReadAllLines to read all lines from a file into a string array.

4fill in blank

hard

Fill both blanks to create a dictionary with word lengths for words longer than 3 characters.

C Sharp (C#)

var lengths = new Dictionary<string, int> { { [1], [2] } };

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

A"example"

B7

C"word"

D4

Attempts:

3 left

💡 Hint

Common Mistakes

Using numbers as keys instead of strings.

Using strings for lengths instead of integers.

The key is a word string and the value is its length as an integer.

5fill in blank

hard

Fill all three blanks to read a file, count lines longer than 5 characters, and print the count.

C Sharp (C#)

var lines = File.[1]("data.txt");
int count = lines.[2](line => line.Length > [3]);
Console.WriteLine(count);

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

AReadAllLines

BCount

C5

DReadAllText

Attempts:

3 left

💡 Hint

Common Mistakes

Using ReadAllText instead of ReadAllLines.

Using wrong method to count lines.

Using wrong length value.

ReadAllLines reads all lines, Count counts lines matching the condition, and 5 is the length threshold.