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

Practice - 5 Tasks

1fill in blank

easy

Complete the code to read all lines from a file into a string array.

C Sharp (C#)

string[] lines = System.IO.File.[1]("example.txt");

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

AGetLines

BReadAllLines

CReadFile

DReadText

Attempts:

3 left

💡 Hint

Common Mistakes

Using a method that does not exist like ReadText or GetLines.

Confusing ReadAllLines with ReadAllText which returns a single string.

The method ReadAllLines reads all lines from a text file and returns them as a string array.

2fill in blank

medium

Complete the code to read the entire content of a file as a single string.

C Sharp (C#)

string content = System.IO.File.[1]("example.txt");

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AReadAllText

BReadAllLines

CReadTextFile

DReadFileContent

Attempts:

3 left

💡 Hint

Common Mistakes

Using ReadAllLines which returns an array of strings.

Using non-existent methods like ReadTextFile.

The method ReadAllText reads the entire file content as one string.

3fill in blank

hard

Fix the error in the code to open a file and read its first line using StreamReader.

C Sharp (C#)

using var reader = new System.IO.StreamReader("example.txt");
string firstLine = reader.[1]();

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AReadAllLines

BRead

CReadToEnd

DReadLine

Attempts:

3 left

💡 Hint

Common Mistakes

Using ReadAllLines which is not a StreamReader method.

Using ReadToEnd which reads the whole file.

The ReadLine method reads the next line from the StreamReader.

4fill in blank

hard

Fill both blanks to read all lines from a file and print only lines longer than 5 characters.

C Sharp (C#)

string[] lines = System.IO.File.[1]("example.txt");
foreach (var line in lines)
{
    if (line.[2] > 5)
    {
        Console.WriteLine(line);
    }
}

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AReadAllLines

BLength

CCount

DReadAllText

Attempts:

3 left

💡 Hint

Common Mistakes

Using ReadAllText which returns a single string, not an array.

Using Count which is not a string property.

ReadAllLines reads all lines into an array. Length gives the number of characters in a string.

5fill in blank

hard

Fill all three blanks to create a dictionary with words as keys and their lengths as values, only for words longer than 3 characters.

C Sharp (C#)

var words = new List<string> { "apple", "cat", "banana", "dog" };
var wordLengths = words.ToDictionary([1] => [2], [3] => [3].Length);
var filtered = wordLengths.Where(kv => kv.Value > 3).ToDictionary(kv => kv.Key, kv => kv.Value);

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Aword

Bw

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names for key and value selectors.

Not using the Length property for the value.

We use a lambda with a variable name for the key selector and value selector. Both use the same variable w. The key is w and the value is w.Length.