1. Nested Loops, Break/Continue

2. Nested Loops Nested loops : loop inside a loop – Loop through rows and columns – Loop through every word in every file – Loop through every number less than every number less than 100

3. Nested Loop Regions Regions for nested loops: – With row major ordering //values available through every row/col for/while each row { //start row //values that start over for each row for/while each value in row { one "cell" } //end row }

4. Nested While Loops Careful with init/update for while loops – Broken Attempt

5. Fixed Whiles Outer loop works with i Inner with j – reset each time

6. Multiplication Table Print this table:

7. Multiplication Table Look for patterns – Have to work in rows

8. Header

9. Body

10. Break Complex exit conditions can get ugly:

11. Break Break exits a loop – Use CAREFULLY to avoid complex conditions

12. Continue Continue skips rest of loop body

13. Continue Keep special case special, normal case normal GoodLess Good for(int i = 10; i >= 1; i--) if( i == 5 ) continue; cout << i; } for(int i = 10; i >= 1; i--) if( i != 5 ) { cout << i; } }

14. Continue With While, must still update! int i = 0; while(i < 10) { if( i == 5 ) { i++; //infinite loop without! continue; } cout << i; i++; }

15. Prime Finder Find/Count primes <= n

16. Starting Point Possible primes: 2…n

17. Starting Point All numbers 2…n

18. Starting Point All numbers 2…n Only print primes… – Not divisible by anything in range 2-(number-1)

19. Starting Point Only print primes… – Not divisible by anything in range 2-(number-1)

20. Merged Code

21. Counting Need to count the primes

22. Counting Need to count the primes

23. Limiting line width Limit to 10 numbers per line – Need new counter – Increment at each print – When hits 10: Print newline Reset counter

24. Limiting line width Limit to 10 numbers per line – Need new counter – Increment at each print – When hits 10: Print newline Reset counter

25. Optimization No need to keep going if we find a factor

26. Other Optimizations No need to test evens – Include 2 always – Start from 3 and count by 2's Only go up to sqrt(n) Use a better algorithm

27. Optimizations Premature optimization is the root of all evil – Code a correct solution first – Take obvious measures to speed code – If needed, fix bottlenecks – High level optimizations trump low level ones