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""" 多行字符串用三个引号 包裹,也常被用来做多 行注释 """
3
1 + 1 8 - 1 10 * 2
35 / 5 5 / 3
5 // 3 5.0 // 3.0 -5 // 3 -5.0 // 3.0
3 * 2.0
7 % 3
2**4
(1 + 3) * 2
True False
not True not False
True and False False or True
0 and 2 -5 or 0 0 == False 2 == True 1 == True
1 == 1 2 == 1
1 != 1 2 != 1
1 < 10 1 > 10 2 <= 2 2 >= 2
1 < 2 < 3 2 < 3 < 2
"这是个字符串" '这也是个字符串'
"Hello " + "world!"
"This is a string"[0]
"{} can be {}".format("strings", "interpolated")
"{0} be nimble, {0} be quick, {0} jump over the {1}".format("Jack", "candle stick")
"{name} wants to eat {food}".format(name="Bob", food="lasagna")
"%s can be %s the %s way" % ("strings", "interpolated", "old")
None
"etc" is None None is None
bool(0) bool("") bool([]) bool({})
print("I'm Python. Nice to meet you!")
some_var = 5 some_var
some_unknown_var
li = []
other_li = [4, 5, 6]
li.append(1) li.append(2) li.append(4) li.append(3)
li.pop()
li.append(3)
li[0]
li[-1]
li[4]
li[1:3]
li[2:]
li[:3]
li[::2]
li[::-1]
del li[2]
li + other_li
li.extend(other_li)
1 in li
len(li)
tup = (1, 2, 3) tup[0] tup[0] = 3
len(tup) tup + (4, 5, 6) tup[:2] 2 in tup
a, b, c = (1, 2, 3)
d, e, f = 4, 5, 6
e, d = d, e
empty_dict = {}
filled_dict = {"one": 1, "two": 2, "three": 3}
filled_dict["one"]
list(filled_dict.keys())
list(filled_dict.values())
"one" in filled_dict 1 in filled_dict
filled_dict["four"]
filled_dict.get("one") filled_dict.get("four")
filled_dict.get("one", 4) filled_dict.get("four", 4)
filled_dict.setdefault("five", 5) filled_dict.setdefault("five", 6)
filled_dict.update({"four":4}) filled_dict["four"] = 4
del filled_dict["one"]
empty_set = set()
some_set = {1, 1, 2, 2, 3, 4}
filled_set = some_set
filled_set_add(5)
other_set = {3, 4, 5, 6} filled_set & other_set
filled_set | other_set
{1, 2, 3, 4} - {2, 3, 5}
2 in filled_set 10 in filled_set
some_var = 5 if some_var > 10: print("some_var比10大") elif some_var < 10: print("some_var比10小") else: print("some_var就是10") """ 用for循环语句遍历列表 打印: dog is a mammal cat is a mammal mouse is a mammal """ for animal in ["dog", "cat", "moouse"]: print("{} is a animal".format(animal)) """ "range(number)"返回数字列表从0到给的数字 打印: 0 1 2 3 """ for i in range(4): print(i) """
while循环直到条件不满足 打印: 0 1 2 3 """ x = 0 while x < 4: print(x) x += 1
try: raise IndexError("This is an index error") except IndexError as e: pass except (TypeError, NameError): pass else: print("All good!")
filled_dict = {"one": 1, "two": 2, "three": 3} our_iterable = filled_dic.keys() print(our_iterable)
for i in our_iterable: print(i)
our_iterable[1]
our_iterable = iter(our_iterable)
our_iterable.__next__()
our_iterator.__next__() our_iterator.__next__()
our_iterator.__next__()
list(filled_dict.keys())
def add(x, y): print("x is {} and y is {}".formatm(x, y)) return x + y 用return语句返回
add(5, 6) add(y=6, x=5)
def varargs(*args): return args varargs(1, 2, 3)
def keyword_args(**kwargs): return kwargs
keyword_args(big="foot", loch="ness")
def all_the args(*args, **kwargs): print(args) print(kwargs) """ all_the_args(1, 2, a=3, b=4) prints: (1, 2) {"a": 3, "b": 4} """ args = (1, 2, 3, 4) kwargs = {"a": 3, "b": 4} all_the_args(*args) all_the_args(**kwargs) all_the_args(*args, **kwargs)
x = 5 def setX(num): x = num print (x) def setGlobalX(num): global x print (x) x = num print (x) setX(43) setGlobalX(6)
def create_adder(x): def adder(y): return x + y return adder add_10 = create_adder(10) add_10(3)
(lambda x: x > 2)(3)
map(add_10, [1, 2, 3]) filter(lambda x: x > 5, [3, 4, 5, 6, 7])
[add_10(i) for i in [1, 2, 3]] [x for x in [3, 4, 5, 6, 7] if x > 5]
class Human(object): species = "H. sapiens" def __init__(self, name): self.name = name
def say(self, msg): return "{name}: {message}".format(name=self.name, message=msg)
@classmethod def get_species(cls): return cls.species
@staticmethod def grunt(): return "*grunt*"
i = Human(name="Ian") print(i.say("hi")) j = Human("Joel") print(j.say("hello"))
i.get_species()
Human.species = "H. neanderthalensis" i.get_species() j.get_species()
Human.grunt()
import math print(math.sqrt(16))
from math import ceil,floor print(ceil(3.7)) print(floor(3.7))
from math import * import math as m math.sqrt(16) == m.sqrt(16)
import math dir(math)
def double_numbers(iterable): for i in iterable: yield i + i
range_ = range(1, 900000000) for i in double_numbers(range_): print(i) if i >= 30: break from functools import wraps def beg(target_function): @wraps(target_function) def wrapper(*args, **kwargs): msg, say_please = target_function(*args, **kwargs) if say_please: return "{} {}".format(msg, "Please! I am poor :(") return msg return wrapper @beg def say(say_please=False): msg = "Can you buy me a beer?" return msg, say_please print(say()) print(say(say_please=True)) }
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