5. Iteration

Repeating a task is one of the most powerful things a program can do. This chapter covers two fundamental loop structures in C# — for and while — and the patterns that make them correct and readable.

Why this chapter matters

Loops are how programs scale from toy examples to real work:

• process every element in a collection without copy-pasting code

• repeat a prompt until the user provides valid input

• compute sums, products, and counts over arbitrary amounts of data

• automate tasks that would be impractical to write out by hand

Learning goals

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

• write counted loops with for and open-ended loops with while

• traverse a string character by character

• use break and continue purposefully

• recognize and avoid infinite loops

Chapter flow

• 5.1. Iteration
• 5.2. The for Statement
• 5.3. foreach Statement
• 5.4. While-Statements
• 5.5. Do-While Loops
• 5.6. Preview Questions
• 5.7. Lab: for Loops
• 5.8. Homework: Grade Calculation
• 5.9. Homework: Grade Calculation from Individual Scores
• 5.10. Chapter Review