Boolean type behavior in C Sharp (C#) - Cheat Sheet & Quick Revision

Recall & Review

beginner

What values can a bool type hold in C#?

A bool type in C# can hold only two values: true or false.

beginner

How does C# treat non-boolean values in conditional statements?

C# does not allow non-boolean values in conditions. For example, integers like 0 or 1 cannot be used directly as conditions; only bool expressions are valid.

beginner

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

The default value of a bool variable is false.

intermediate

Explain short-circuit evaluation with && and || operators in C#.

In C#, && (AND) and || (OR) operators use short-circuit evaluation. This means the second operand is evaluated only if needed. For example, in a && b, if a is false, b is not checked.

intermediate

Can you convert a bool to an integer directly in C#?

No direct cast from bool to int. Use Convert.ToInt32(myBool) or conditional expressions, e.g., int x = myBool ? 1 : 0;.

Which of the following is a valid bool value in C#?

A 1

B true

C "false"

D 0

Only true and false are valid bool values in C#.

What happens if you try to use an integer directly in an if condition in C#?

A It causes a compile-time error.

B It treats all integers as true.

C It works like in C, where 0 is false and non-zero is true.

D It treats all integers as false.

C# requires a bool expression in conditions; integers cannot be used directly.

What is the default value of a bool field in a class if not initialized?

A Undefined

B true

C null

D false

Boolean fields default to false if not explicitly initialized.

In the expression a && b, when is b evaluated?

A Always

B Never

C Only if <code>a</code> is true

D Only if <code>a</code> is false

b is evaluated only if a is true because of short-circuit evaluation.

How can you convert a bool variable flag to an integer 1 or 0?

A int x = flag ? 1 : 0;

B int x = (int)flag;

C int x = Convert.ToInt32(flag);

D int x = flag + 0;

Both the conditional (ternary) operator and Convert.ToInt32(flag) safely convert bool to int (1 for true, 0 for false). Direct casting does not work.

Describe how C# handles boolean values and their use in conditional statements.

Think about what values are allowed and how conditions work.

Explain short-circuit evaluation in C# boolean operators and why it matters.

Consider when the second part of a condition runs.