ShmoopTube

00:00

Thank you We sneak And here's your shmoop du jour

00:05

brought to you by flooring values but not the kind

00:08

you find at the used carpet place All right what

00:11

is the value of numb to after the following code

00:14

is executed All right And here the potential answers Here

00:22

we go It looks like that bit of code converts

00:24

to a value from its initial data type of double

00:28

two imager than to double again and back to imager

00:31

So the key here is in knowing what happens the

00:33

values when you convert values between data types but wait

00:36

isn't a number just a number Well why is the

00:39

imager six eight four four different from the double six

00:43

eight for four why're there different data types at all

00:48

Well the answer lies in your computer's memory or more

00:50

accurately how your computer treats these different types Imagers air

00:55

pretty simple data types They use thirty two bits four

00:57

bites of memory to store a numeric value ranging from

01:01

around two million ish or so to negative two million

01:04

ish space is limited however so there's no room in

01:08

those thirty two bits to stored decimals it's all whole

01:11

numbers A double uses twice the amount of computer memory

01:15

Sixty four bits or eight bites Now there's room for

01:18

decimals and way way larger values But at what cost

01:22

Well because computer memory is not infinite all those bits

01:25

at if we're not calculating extremely large numbers or decimal

01:28

values in our program were probably wasting our memory by

01:31

using doubles Another important thing to know is when you

01:34

converted data type with a decimal such as a double

01:37

to an imager you not only lose the decimal but

01:39

the number is floored rather than rounding to the nearest

01:43

number That means even if you're converting a double like

01:46

four point nine three into an imager it comes out

01:49

to four rather than the five you might have otherwise

01:51

expected So think of it like a huge gnarly acts

01:55

like sing the numbers decimal point off with no regard

01:58

for what's on the right side of it Yeah you

02:00

ever been to a circumcision been like that now let's

02:04

get to the bottom of our problem starting with the

02:06

innermost parenthesis into being negative Three point five gives us

02:11

negative three because again we're flooring it and watch your

02:15

fingers or other important body parts Then we do negative

02:18

three times point five and convert it to a double

02:21

so that'll be negative One point five negative one point

02:24

five converted to an injurious florid against we get negative

02:27

one and our answer is b and hey watch Where 00:02:30.46 --> [endTime] you're swinging that thing pal

Full Transcript