Oto podzbiór składni Pythona, której używamy w naszym kursie. Oto wersja .pdf do druku.
3 * 4, 3 + 4, 3 - 4, 3 / 4 #==> 12, 7, -1, 0.75
3 ** 4, 3 // 4, 3 % 4 #==> 81, 0, 3
4 > 3, 4 >= 3, 3 == 3.0, 3 != 4, 3 <= 4 #==> True, True, True, True, True
# order of operations: brackets, **, {* / // %}, {+ -}, {== != <= < > >=}
min(3, 4), max(3, 4), abs(-10) #==> 3, 4, 10
sum([1, 2, 3]) # [1, 2, 3] is a list #==> 6
type(3), type(3.0), type("myVariable") #==> class 'int', class 'float',
# class 'str'
int("4"+"0"), float(3), str(1 / 2) #==> 40, 3.0, '0.5'
"double quotes: ', escaped \" \\ \'" #==> double quotes: ', escaped " \ '
'it\'s "similar" in single quotes ' #==> it's "similar" in single quotes
ord("A"), chr(66) #==> 65, 'B'
string = "hello"
# the following statements work for lists too
len(string) #==> 5
string[0], string[4] # get characters #==> "h", "o"
string[1:3] # get a substring #==> "el"
string[:2], string[2:] # l/r substrings #==> "he", "llo"
string[-1], string[-2:] # negative indices#==> "o", "lo"
"con" + "cat" + "enation " + str(123) #==> "concatenation 123"
"boo" * 2 #==> "booboo"
getLineOfInputAsString = input() #==> read input (or EOF error)
print("takes", 0, "or more arguments") #==> takes 0 or more arguments
print("using", "custom", "sep", sep=".") #==> using.custom.sep
print("no", "newline", end="bye") #==> no newlinebye
not True, False or True, False and True #==> False, True, False
# order of operations: brackets, {== !=}, not, and, or
if booleanCondition:
x # indent the body block
x # every line by the same amount
elif anotherCondition: # can do zero, one, or several elif blocks
x # multi-line block
else: # optional
x # multi-line block
while booleanCondition:
x # the body block
break # jump out (optional)
continue # restart from top of next iteration (optional)
for indexVariable in range(low, highPlus):
print(indexVariable) #==> low, low+1, ..., highPlus-1
# "for item in listOrString:" forall/foreach loops
# break, continue can be used in for loops
def nameOfNewFunction(argument1, argument2):
x # the body block
return y # (optional; if you don't return, it returns None)
def remember(bar): # writing to global variables
global saveBar # after calling foo(3), saveBar = 3
saveBar = bar # even outside of the function's scope
# these 'slice' commands have analogues for lists and range()
"0123456789"[::2] # slices #==> "02468"
"0123456789"[::-1] # descending #==> "9876543210"
"0123456789"[6:3:-1] #==> "654"
x += 1 # also -=, /=, *=, %=, **=, //=. Python has no C++-style "x++"
x, y = y, x # multiple assignment
3 < x < 5 # same as "(3 < x) and (x < 5)". can chain {< <= > >= == != is}
import math # import, to get everything with period
print(math.sqrt(2))
from math import sqrt # import, to get one thing without period
print(sqrt(2))
# also in math module: pi, exp, log, sin, cos, tan, ceil, floor, and more
list = ['zero', 'one', 'two']
list.index('one') #==> 1
list.index('three') #==> causes an error
'three' in list, 'zero' in list #==> False, True
list.count('two') #==> 1
del list[1] # list becomes ['zero', 'two']
"string" in "superstring" #==> True
"superstring".index("string") #==> 5
# more list methods: append(item), insert(index, item), extend(list),
# remove(value), pop(), pop(index), reverse(), sort(), and more
# some string methods: capitalize(), lower/upper(), islower/isupper(),
# isalpha/isdigit(), center/ljust/rjust(width, fillChar), strip(), split(),
# splitlines(), endswith/startswith(string), find(string), replace(old, new),
# and more
myList = [11, 99]
actuallyTheSameList = myList # not a true copy! just copies the reference
myList is actuallyTheSameList #==> True
realCopy = myList[:] # or list(myList), copy.copy(myList), deepcopy
realCopy is myList #==> False
