C# Loops
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For loops allow code to be repeatedly executed until a condition is met. They include initialization, condition, and update statements. While and do-while loops also repeatedly execute code until a condition is met, but check the condition at the start or end of each iteration respectively. Loops are useful for tasks like adding numbers in a range or populating data structures to avoid repetitive code.
C# Loops
- 1. Chapter 6C# .NET Loops
- 2. What will you be learning?For loopsWhile loopsDo loops
- 3. What is a loop?A loop is a way to execute a piece of code repeatedly Go round and round until an end condition is met
- 4. Why use loops?Eg: you need to add from 0 to 10 Solution not using loop:int answer; answer = 0 + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10; The above solution not suitable for very large numbers (says from 0 to 10000) – programmers are lazy, what would be a faster way to solve?
- 5. Flowchart “for” loopStart with i = 0End when i is not < 101Update i by adding 1
- 6. for loopfor ( ) // start, end, update conditions{ // Processing}
- 7. for loopfor (inti=0; i < 101; i++ ) { // Processing}
- 8. for (inti=0; i < 101; i++ ) Write syntax of the following for loopsFrom j = 10 until j = 1000 (inclusive), update j by 1 for each loopFrom t = 2 until t = 1000 (inclusive), update t by 2 for each loopFrom m = 5 until m = 0 (inclusive), update m by -1 for each loop
- 9. Exercise Part 1 – For LoopsAdd a new project to “Part 1 For Loops”Put one button and add the following codes for its click method (pg 112):
- 10. Exercise Part 1 – For Loops
- 11. Exercise Part 2Loop Start Values and Loop End Values Add a project “Part 2” to the solution
- 12. Do it yourself - TimeTableModify the previous projectTo add item to the listBox: listBox1.Items.Add("xxxx")To clear the listBox: listBox1.Items.Clear( );
- 13. break continueAdd new project to SpfChapter6 solution: “Extra – break and continue”Add a button and add codes into its Click method: for (int x=0; x < 11; x++){ if (x==5) break;MessageBox.Show(“x =”+x);}
- 14. break continuefor (int x=0; x < 11; x++){ if (x==5) continue;MessageBox.Show(“x =”+x);}
- 15. while loopwhile ( ) // End condition {}
- 16. while loopinti = 0;while (i < 101){// Processing :i++; // at the end}
- 17. do loopdo{} while ( ); // End condition// The difference between the while(){.. } and Do {..} while(); loops is that the code in a Do loop will get executed at least once, because its while part is at the end.
- 18. do loopinti = 0;do{// Processing :i++; // at the end} while (i < 101);
- 19. Part 3Modify the previous projectChange from "for" loop to “while” and then to "do while" loop
- 20. SummaryA loop is a way to execute a piece of code repeatedly We shall be using loops again when we cover ArraysThere is also "foreach" loop that applies for string, array and objects