Why string handling matters in C Sharp (C#) - Challenge Your Understanding

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this string manipulation code?

Look at this C# code that changes a string. What will it print?

C Sharp (C#)

string text = "Hello World";
string result = text.Replace("World", "C#");
Console.WriteLine(result);

A Hello

B Hello C#

C HelloWorld

D Hello World

💡 Hint

Think about what the Replace method does to the string.

The Replace method swaps the word "World" with "C#" in the original string, so the output is "Hello C#".

❓ Predict Output

intermediate

What does this code print when trimming spaces?

This code trims spaces from a string. What will it print?

C Sharp (C#)

string input = "  C# Programming  ";
string trimmed = input.Trim();
Console.WriteLine(trimmed.Length);

A 15

B 17

C 19

D 13

💡 Hint

Count the characters after removing spaces at the start and end.

The original string has spaces at start and end. Trim() removes them, leaving "C# Programming" which has 14 characters.

🔧 Debug

advanced

Which option causes a runtime error in string indexing?

Check these code snippets that access characters in a string. Which one will cause an error when run?

C Sharp (C#)

string s = "Code";
char c = s[4];

A char c = s[4]; // Access out of range

B char c = s[3]; // Access last character

C char c = s[0]; // Access first character

D char c = s[s.Length - 1]; // Access last character

💡 Hint

Remember string indexes start at 0 and go to length-1.

Index 4 is outside the string "Code" which has indexes 0 to 3, so accessing s[4] causes an IndexOutOfRangeException.

🧠 Conceptual

advanced

Why is string immutability important in C#?

Strings in C# cannot be changed after creation. Why is this useful?

A It improves performance by allowing safe sharing of strings without copying.

B It allows strings to be changed anywhere without restrictions.

C It makes strings slower to use because they cannot be modified.

D It prevents strings from being used in collections.

💡 Hint

Think about safety and efficiency when many parts of a program use the same string.

Immutable strings can be shared safely without risk of changes, which improves performance and thread safety.

❓ Predict Output

expert

What is the output of this complex string formatting code?

Analyze this C# code that formats a string with variables. What will it print?

C Sharp (C#)

int count = 3;
string item = "apple";
string output = $"I have {count} {item}{(count > 1 ? "s" : "")}.";
Console.WriteLine(output);

A I have 3 apple(s).

B I have 3 apple.

C I have 3 apples.

D I have apples3.

💡 Hint

Look at how the conditional adds an 's' only if count is more than 1.

The code adds 's' to 'apple' because count is 3, so the output is "I have 3 apples."