4. Conditionals

Programs need to make decisions. This chapter introduces the core decision-making constructs in C#: if, else if, else, switch, and the boolean expressions that drive them.

Why this chapter matters

A program that always does the same thing regardless of its inputs has limited value. Conditionals unlock real behavior:

• validate user input before using it

• pick the right code path for each situation

• express business rules such as grade cutoffs or access levels

• combine multiple conditions with &&, ||, and !

Learning goals

By the end of this chapter, you should be able to:

• write if, else if, and else chains correctly

• construct boolean expressions using comparison and logical operators

• handle multiple exclusive cases with a switch statement

• avoid common pitfalls: dangling else, off-by-one comparisons

Chapter flow

• 4.1. Boolean Expressions & Logical Operators
• 4.2. Conditional (if) Statements
• 4.3. Switch Statement
• 4.4. Preview Questions
• 4.5. Lab 04
• 4.6. Chapter Review