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Python ??????????B??

Python ????????????????????????????????Python ????????????????????????????????????????? Python ?????????????????????

1. for-else????????

??? Python ????????????? else ?? if ????????else ???? for??????for-else ????????????????????

for i in [1,2,3,4]:
    print(i, "??else")
else:
    print("??else")

????? 1 ??else 2 ??else 3 ??else 4 ??else ??else

????????????????????????break?????else???

2. ???(*)????(**)

???????? Python ???????? (*) ????????????? (**) ????????????????

def multi_sum(*args):
    s = 0
    for item in args:
        s += item
    return s
multi_sum(3,4,5)  # ??12

???????????????????????????????????????

def do_something(name, age, gender='?', *args, **kwds):
    print("??? %s????%d????%s" % (name, age, gender))
    print(args)
    print(kwds)

3. ?????????????????

?????? Python ???????????????????????expression if condition else expression????

y = 5
print("y?????" if y < 0 else "y??????")

?????y??????

??????????????????????????

4. with - as??????????

with ??????????????????? with ??????????????????????

with open(r"D:\CSDN\Column\temp\mpmap.py", 'r') as fp:
    contents = fp.readlines()

???????? try-finally ??????????????

5. ?????????????

?????????????????????????????????????????????

a = [1,2,3,4,5]
result = [i*i for i in a]

???????? for ????????????????

6. ???????????

Python ????????????????????????????

a = [0,1,2,3,4,5]
a[2:4]  # [2,3]
a[3:]   # [3,4,5]
a[1:]   # [1,2,3,4,5]
a[:]    # [0,1,2,3,4,5]

??????????????????????????????

7. lambda ??????????

lambda ??????????????????????

lambda x, y: x + y

???????????????????????????????

8. yield ?????????

yield ???????????????????????????????????

def get_square(n):
    for i in range(n):
        yield pow(i,2)

???????????????????????????

9. ?????????????

????????????????????????????????????

import time
def timer(func):
    def wrapper(*args, **kwds):
        t0 = time.time()
        func(*args, **kwds)
        t1 = time.time()
        print('??%0.3f' % (t1-t0,))
        return wrapper

???????????????????????????

10. ?? assert????????

?? assert ??????????????????

def i_want_to_sleep(delay):
    assert isinstance(delay, (int, float)), '?????????????'
    print('????')
    time.sleep(delay)
    print('???')

?????????????????????????????

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Python ?????????????????????????????????????????????????????????????????????????? Python ??????????????????????????

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