Default values for types in C Sharp (C#) - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the default value of an int in C#?

The default value of an int is 0.

beginner

What is the default value of a bool in C#?

The default value of a bool is false.

beginner

What is the default value of a reference type like string in C#?

The default value of a reference type such as string is null.

intermediate

How can you get the default value of any type T in C#?

You can use the expression default(T) to get the default value of type T.

beginner

What is the default value of a double in C#?

The default value of a double is 0.0.

What is the default value of a char in C#?

A null

B ' ' (space)

C 'a'

D '\0' (null character)

The default value of a char is the null character '\0', which is the Unicode character with code zero.

Which of these types has a default value of null in C#?

A string

B bool

C int

D double

Reference types like string have a default value of null. Value types like int, bool, and double have non-null default values.

What does the expression default(bool) return?

A true

B false

C null

D 0

default(bool) returns false, which is the default value for the bool type.

How do you get the default value of a generic type T in C#?

A default(T)

B T.default

C null

D new T()

The correct way to get the default value of a generic type T is to use default(T).

What is the default value of a decimal type in C#?

A 0.0

B null

C 0

D 0.0m

The default value of decimal is 0. The suffix m is used for literals but not for default values.

Explain what default values are in C# and give examples for both value and reference types.

Think about what happens when you declare a variable but don't assign a value.

How can you use the default keyword with generic types in C#? Why is it useful?

Consider how you write code that works with any type.