Python - Its Functuns and Syntax

8/14/2019 Python - Its Functuns and Syntax

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FUNCTIONSITS TIME TO BE ORGANISED


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TO THE

RESCUEPOINT

As programs grow, the code often becomesmore compe!" How to cope #p $


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Dont duplicate your data

instead REUSE it using FUNTIONS


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A na!ed se"uence o# state!entst$at per#or!s so!e use#ul

operation%

%hat &s a f#nct&on $


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For e%g% &>>> type(32)

< type int >

'ere(Function na!e& type

Argu!ent passed& )*


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For e%g% &

val=50

>>> type(val)

< type int >

'ere(

Function name& type

Argument passed& +al ,parameter-

Anot$er e.a!ple


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/yt$on pro+ides 0uilt1in #unctions t$atcon+ert +alues #ro! one type to anot$er%

For e%g% &

>>> int(3.)3 !!output

T'pe con(ers&ons

#loat int


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T$e int #unction ta2es any +alue and converts

it to an integer( i# it can( or complainsot$er3ise&

For e%g% &

>>> int("#ello")

$alue%rror& invalid literal 'or int()& #ello


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T$ere are * types o# #unctions &

4% In0uilt types

*% User1de#ined

T)PES OF FUNCTIONS


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/yt$on $as modulest$at pro+ide !ost o#t$e #a!iliar #unctions%

A moduleis a 5le t$at contains a collectiono# related #unctions%

For e%g% &

Mat$ !odule

IN*UI+T FUNCTIONS


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speci#y t$e na!e o# t$e !odule and t$ena!e o# t$e #unction( separated 0y a dot%

T$is #or!at is called dot notation%

For e%g% &

>>> radians = 0.

>>> eigt = mat.sin(radians)

How to access f#nct&ons from

mod#es$


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Functions de#ined 0y t$e user as per $isre"uire!ents are called user de#ined#unctions%

User def&ned F#nct&ons


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def twice(number):

Finds the twice of the number .

int answer

answer=2*number

return answer

ef&n&ng a f#nct&on


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>>>def twice(number):

Finds the twice of the number .

int answer answer=2*number

return answer

Aternat&(e


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efde#ines a #unction numbersis a para!eter & a +aria0le used to

$old an argu!ent T$is doc string tells 3$at t$e #unction does A #unction t$at co!putes a +alue !ust returnit

twice(101) 3ill return *6*%

>>> ef twice(number): Fin s the twice of the number . int answer

answer=2*number return answer


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So!e o# t$e #unctions yield results 3$ileso!e not%

FRUITFU+ and -OI FUNCTIONS


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For e%g% &

777 type,)*-

8 type 9 int 9 7

*is is a void 'unction as it not return anyvalue.


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For e.. :def twice(number):

Finds the twice of the number int answer

answer=2*numberreturn answer

!his function returns a "a#ue bac$ to the

main. %o this a fruitfu# function.


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A #unction call is li2e a detour in t$e :o3 o#e.ecution% Instead o# going to t$e ne.t

state1 !ent( t$e :o3 ;u!ps to t$e 0ody o#t$e #unction( e.ecutes all t$e state!entst$ere( and t$en co!es 0ac2 to pic2 up3$ere it le#t o##%

E!ec#t&on of f#nct&ons


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< =e can na!e a group o# state!ents( 3$ic$!a2es our progra! easier to read andde+ug% Functions can !a2e aprogram smaller 0y

eli!inating repetiti+e code% >ater( i# you!a2e a c$ange( you only $a+e to !a2e itin one place%

=ell1designed #unctions are o#ten use#ul#or !any progra!s% Once you 3rite andde0ug one( you can reuseit%

%h' f#nct&ons$


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=$en a #unction calls anot$er #unction%

Nested F#nct&ons


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For e.. :

def twice(number):

Finds the twice of the number

int answeranswer=2*numberreturn answer

def twice&s'uare(number):

Finds the s'uare of twice of the numberint t

int answer

t=twice(number) answer=t*t

return answer777t3ice?s"uare,*6-4@66


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RECURSION

*e a+ility o' a 'unction to callitsel' is called ,%-,/1.


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)

*4

Blasto##

For e"g" .def co#ntdown/n0.

&f n 12 3.pr&nt 4*astoff54

ese.pr&nt n co#ntdown/n670

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Python - Its Functuns and Syntax