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Grundlæggende Operatører


This section explains how to use basic operators in Python.

Aritmetiske Operatorer

Ligesom i andre programmeringssprog kan additions-, subtraktions-, multiplikations- og divisionsoperatorerne bruges med tal.

number = 1 + 2 * 3 / 4.0
print(number)

Prøv at forudsige, hvad svaret vil være. Følger Python rækkefølgen af operationer?

En anden tilgængelig operator er modulo (%) operatoren, som returnerer heltalsresten af divisionen. dividende % divisor = rest.

remainder = 11 % 3
print(remainder)

Ved at bruge to multiplikationssymboler dannes et potensforhold.

squared = 7 ** 2
cubed = 2 ** 3
print(squared)
print(cubed)

Brug af Operatorer med Strenge

Python understøtter sammenkædning af strenge ved brug af additionsoperatoren:

helloworld = "hello" + " " + "world"
print(helloworld)

Python understøtter også multiplikation af strenge for at danne en streng med en gentagende sekvens:

lotsofhellos = "hello" * 10
print(lotsofhellos)

Brug af Operatorer med Lister

Lister kan sammenføjes med additionsoperatoren:

even_numbers = [2,4,6,8]
odd_numbers = [1,3,5,7]
all_numbers = odd_numbers + even_numbers
print(all_numbers)

Ligesom med strenge understøtter Python at danne nye lister med en gentagende sekvens ved brug af multiplikationsoperatoren:

print([1,2,3] * 3)

Øvelse

Målet med denne øvelse er at oprette to lister kaldet x_list og y_list, som indeholder 10 forekomster af variablerne x og y, henholdsvis. Du skal også oprette en liste kaldet big_list, som indeholder variablerne x og y, 10 gange hver, ved at sammenkæde de to lister, du har oprettet.

x = object() y = object() # TODO: change this code x_list = [x] y_list = [y] big_list = [] print("x_list contains %d objects" % len(x_list)) print("y_list contains %d objects" % len(y_list)) print("big_list contains %d objects" % len(big_list)) # testing code if x_list.count(x) == 10 and y_list.count(y) == 10: print("Almost there...") if big_list.count(x) == 10 and big_list.count(y) == 10: print("Great!") x = object() y = object() # TODO: change this code x_list = [x] * 10 y_list = [y] * 10 big_list = x_list + y_list print("x_list contains %d objects" % len(x_list)) print("y_list contains %d objects" % len(y_list)) print("big_list contains %d objects" % len(big_list)) # testing code if x_list.count(x) == 10 and y_list.count(y) == 10: print("Almost there...") if big_list.count(x) == 10 and big_list.count(y) == 10: print("Great!") Ex().check_object('x_list').has_equal_value(expr_code = 'len(x_list)') Ex().check_object('y_list').has_equal_value(expr_code = 'len(y_list)') Ex().check_object('big_list').has_equal_value(expr_code = 'len(big_list)') success_msg('Good work!')

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