AP Computer Science 2.3 Review of the Basics

right And here your potential answers Okay true false got

it All right let's Go let's take a look at

what this code segment is trying to do First we

get two double variables The first being given the value

of ten and a second being given the value of

zero Then we start a loop The loop begins counting

with inger i zero halt when i stopped being less

than fifty and increases i buy one each time the

loop like once inside the loop will be adding point

to numb teo over and over and over again fifty

times total since that's how long our loop will run

afterwards we'll have three statements Print results of a few

operations were the first prints the tour false results of

whether numb one equals to the second print through her

false based on whether numb one divided by two equals

one same number and not zero And the third prince

true or false depending on whether numb one minus number

two equal zero again away to check if they're the

same number So let's try and predict the kinds of

results will get All right Back up to our loop

We've got numb to starting out equal to zero and

we add point two two it fifty times Well in

california fifty towns point two is ten so after the

loop is finished running canting treating tonight someone in them

too should both be tense And if we plug that

into our print statements we'd get numb One equals dumb

two or ten equals ten True can divide by ten

equals one true and minus ten equals zero True but

way Just hold your horses one sec If you got

your handy compiler you can pause the video here and

try running the code yourself and no seriously give the

shot will wait here's the code again and a picture

of a cold er Yesterday all my troubles seemed so

far ready All right So what did you find out

Well for those of you who didn't run the code

this is what happened Falls all falls which is our

answered the question by the way option he but wait

Why Tennis Ten right there's Not much That could possibly

go wrong with the statement Tennis Just ten even in

california with all you communists out there But i will

unless tennis somehow not ten Well let's add a line

to the end of the snippet to investigate a little

more closely We'll have it print the actual value of

numb to to make sure we're getting the ten that

we paid for system out print line none too And

go well ten is not ten it's Very very close

But it's just not in this case It's like nine

point nine nine nine nine nine six something that's why

our statements returned false and it's Not even a bug

issue here has to do with the very nature of

floating point arithmetic Those double variables we declared earlier and

more formally known as double precision floating point variables which

is to say is not quite as solid as an

imager it's More like an approximation of a real number

This has its uses when dealing with very complicated numbers

that don't quite need to be perfectly exact The distance

to the next galaxy over for example like that But

when you're dealing with the values that need to be

concrete like money do yourself a favor and compute using

interest or long otherwise you're going to be going people

One craw drill yin of a penny and your knives 00:03:32.22 --> [endTime] probably aren't that shark even against you