String interpolation and formatting in C Sharp (C#) - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of string interpolation with expressions

What is the output of the following C# code?

C Sharp (C#)

int a = 5;
int b = 3;
string result = $"Sum of {a} and {b} is {a + b}";
Console.WriteLine(result);

A Sum of a and b is a + b

B Sum of 5 and 3 is 8

C Sum of 5 and 3 is a + b

D Sum of 5 and 3 is 53

💡 Hint

Remember that expressions inside { } in interpolated strings are evaluated.

The variables a and b are replaced by their values 5 and 3, and the expression a + b is evaluated to 8 inside the interpolated string.

❓ Predict Output

intermediate

Formatting numbers with string interpolation

What will be printed by this C# code?

C Sharp (C#)

double pi = 3.14159;
string formatted = $"Pi rounded to 2 decimals: {pi:F2}";
Console.WriteLine(formatted);

A Pi rounded to 2 decimals: 3.14

B Pi rounded to 2 decimals: 3.14159

C Pi rounded to 2 decimals: 3.1

D Pi rounded to 2 decimals: 3

💡 Hint

The :F2 format specifier rounds to 2 decimal places.

The format specifier F2 formats the double to 2 decimal places, so 3.14159 becomes 3.14.

❓ Predict Output

advanced

Aligning text with string interpolation

What is the output of this C# code snippet?

C Sharp (C#)

string name = "Bob";
string output = $"|{name,10}|{name,-10}|";
Console.WriteLine(output);

A |Bob|Bob|

B |Bob | Bob|

C | Bob| Bob|

D | Bob|Bob |

💡 Hint

Positive numbers align right, negative numbers align left in interpolation.

The {name,10} aligns the string right in a 10-character field, adding spaces on the left. The {name,-10} aligns left, adding spaces on the right.

❓ Predict Output

advanced

Custom numeric format strings in interpolation

What will this C# code print?

C Sharp (C#)

int number = 42;
string formatted = $"Number with leading zeros: {number:D5}";
Console.WriteLine(formatted);

A Number with leading zeros: 42000

B Number with leading zeros: 42

C Number with leading zeros: 00042

D Number with leading zeros: 0000042

💡 Hint

The D5 format pads the number with zeros to make it 5 digits long.

The D5 format specifier means decimal with at least 5 digits, so 42 becomes 00042.

🧠 Conceptual

expert

Understanding escape sequences in interpolated strings

Which option correctly shows how to include a literal brace character '{' in a C# interpolated string?

A string s = $"This is a brace: {{";

B string s = $"This is a brace: {";

C string s = $"This is a brace: \{";

D string s = $"This is a brace: '{'";

💡 Hint

In interpolated strings, double braces {{ or }} are used to escape braces.

To include a literal brace in an interpolated string, you must double it. So {{ outputs a single { character.