ICS 3U

1. ICS 3U The Counted Loop FOR LOOPS

2. For Loops - Introduction Loops are used to repeat a block of statements. A For Loop is used to execute the statements inside a fixed number of times. A For Loop in ActionScript looks like: for (initialization; condition; increment) { Statement(s) to be repeated } Initialization performed only the first time the loop is executed, sets the starting value of the variable that is used to control the loop Condition a Boolean expression that is evaluated before each execution of the loop, tells when to stop the loop Increment performed after each execution of the loop, it advances the value of the loop control variable

3. For Loops - Example A Simple Count to 10 vari: int; for (i =0; i <= 10; i++)  adds one { trace(i); }

4. For Loops – Example Counting Backwards 10 to 1 vari: int; for (i = 10; i >=0; i--)  subtracts one { trace(i); }

5. For Loops - Example Generating 25 random numbers between 1 and 100 varrandnum: int; vari: int; varhigh:int = 100; var low: int = 1; for (i = 0; i <= 25; i++) { randnum = Math.floor(Math.random ...); trace (randnum); }

6. For Loops - Example Write a For Loop that will: Output all numbers between 1 and 100 that are divisible by 3.

7. Additional Notes • Can I only increment my loop control variable by 1? Can I go up by 5’s? 2’s? • A single letter variable?! • we typically use these as loop control variables in the for loops (counted loops). • It is ok in these instances • Accumulators • Many times in loops we want to accumulate a value. Keep a running total, keeping a score, counting the number of even numbers, etc.

8. Accumulators Write a for loop that will total 5 random numbers generated. Can also use subtract: newvalue= newvalue – randnum; OR newvalue -= randnum;

9. Exercises See Website for the exercises ... NOW – Get to WORK!!