More Repetition While and For Loops SentinelControlled Loops

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More Repetition While and For Loops Sentinel-Controlled Loops Intro to Computer Science CS 1510

More Repetition While and For Loops Sentinel-Controlled Loops Intro to Computer Science CS 1510 Dr. Sarah Diesburg

Today’s Agenda Exploring looping alternatives For and While loops Sentinel-Controlled vs Count-Controlled loops

Today’s Agenda Exploring looping alternatives For and While loops Sentinel-Controlled vs Count-Controlled loops

Loops Count-controlled loop, which means we will know in advance how many times the

Loops Count-controlled loop, which means we will know in advance how many times the loop will run Sentinel-controlled loop, which means we do not know in advance how many times the loop will run Controlled by sentinels Event-controlled 3

For Loops for var. Name in iterable. Data. Structure: (next thing in Data. Structure

For Loops for var. Name in iterable. Data. Structure: (next thing in Data. Structure put in var. Name) suite of code Is a for loop count-controlled or sentinelcontrolled? 4

While Loops while boolean expression: statement. Suite If while loop is count-controlled, will it

While Loops while boolean expression: statement. Suite If while loop is count-controlled, will it contain some kind of counter? 5

Let’s go through a countcontrolled example… Finish looking at ways to repeat from last

Let’s go through a countcontrolled example… Finish looking at ways to repeat from last time… Annoying kid in the car (cartrip. py) 6

Moving to Sentinel Controlled For loops are always count-controlled Every for loop could be

Moving to Sentinel Controlled For loops are always count-controlled Every for loop could be written as a while loop (although usually a little more complicated to set up) While loops can behave like count controlled loops (kid in the car from this week) but also as sentinel-controlled loops (average quiz score from this week).

Let’s go back to Tuesday’s Lab The “challenge” of using a while loop is

Let’s go back to Tuesday’s Lab The “challenge” of using a while loop is that it is a pre-test solution. That is, you have to have some data to work with Several solutions to the “average” problem Adjusting for the extra loop (example 1) Using a “loop and a half” (example 2) Infinite loops with a break statement (example 3)

Let’s look at some code

Let’s look at some code