Composite formatting in C Sharp (C#) - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of composite formatting with multiple placeholders

What is the output of the following C# code using composite formatting?

C Sharp (C#)

string result = string.Format("{0} scored {1} out of {2}.", "Alice", 85, 100);
Console.WriteLine(result);

A Alice scored 85 out of {2}.

B Alice scored 85 out of 100.

C 0 scored 85 out of 100.

D Alice scored {1} out of {2}.

💡 Hint

Look at how placeholders {0}, {1}, and {2} are replaced by the arguments in order.

Composite formatting replaces placeholders {0}, {1}, {2} with the first, second, and third arguments respectively. So {0} becomes "Alice", {1} becomes 85, and {2} becomes 100.

❓ Predict Output

intermediate

Composite formatting with alignment and padding

What is the output of this C# code using composite formatting with alignment?

C Sharp (C#)

string result = string.Format("|{0,10}|{1,-5}|", 42, "Hi");
Console.WriteLine(result);

A | 42|Hi |

B |42 | Hi|

C |42|Hi|

D | 42| Hi|

💡 Hint

Positive alignment pads left side with spaces, negative pads right side.

The first placeholder {0,10} pads the number 42 to the left with spaces to fill 10 characters. The second {1,-5} pads "Hi" to the right with spaces to fill 5 characters. So the output is "| 42|Hi |".

🔧 Debug

advanced

Identify the error in composite formatting

What error does this C# code produce when run?

C Sharp (C#)

string result = string.Format("{0} {1} {2}", "one", "two");
Console.WriteLine(result);

A System.FormatException: Index (zero based) must be greater than or equal to zero and less than the size of the argument list.

B No error, output: one two {2}

C Output: one two

D Output: one two {2}

💡 Hint

Check if the number of placeholders matches the number of arguments.

The format string expects three arguments for placeholders {0}, {1}, and {2}, but only two arguments are provided. This causes a System.FormatException at runtime.

🧠 Conceptual

advanced

Understanding format specifiers in composite formatting

What is the output of this C# code using composite formatting with a format specifier?

C Sharp (C#)

double pi = 3.14159;
string result = string.Format("Pi rounded: {0:F2}", pi);
Console.WriteLine(result);

A Pi rounded: F2

B Pi rounded: 3.14159

C Pi rounded: 3

D Pi rounded: 3.14

💡 Hint

The format specifier F2 means fixed-point with 2 decimal places.

The format specifier F2 rounds the number to 2 decimal places, so 3.14159 becomes 3.14 in the output.

❓ Predict Output

expert

Composite formatting with nested braces and escaped characters

What is the output of this C# code using composite formatting with escaped braces?

C Sharp (C#)

string result = string.Format("{{0}} is not a placeholder, but {0} is.", 123);
Console.WriteLine(result);

A {0} is not a placeholder, but {0} is.

B 0 is not a placeholder, but 123 is.

C {0} is not a placeholder, but 123 is.

D System.FormatException

💡 Hint

Double braces {{ and }} are used to escape braces in composite formatting.

Double braces {{ and }} output a single brace character. So "{{0}}" outputs "{0}" literally, while {0} is replaced by 123.