The path to python: wupeiqi

The path to python: wupeiqi

1. Non-fixed function parameters

* Args * kwargs

1 def test (* args): 2 print (args) 3 4 test (1, 2, 3, 4, 5) 5 test (* [1, 2, 3, 4, 5]) # * args = * [1, 2, 3, 4, 5] args = tuple ([1, 2, 4, 5]) 6 l = [1, 2, 3] 7 test (* l) 8 9 def test1 (x, * args): 10 print (x) 11 print (args) 12 test1 (1, 2, 3, 4, 5, 6, 7) 13 14 # ** kwargs, convert n keyword parameters to the dictionary in the following way: 15 def test2 (** kwargs): 16 print (kwargs) 17 test2 (name = 'jiachen', age = 27) 18 d = {'name': 'jiachen', 'age': 27} 19 test2 (** d) 20 21 def test3 (x, * args, ** kwargs ): 22 print (x) 23 print (args) 24 print (kwargs) 25 test3 (1, * [2, 3, 4], ** {'name': 'jiachen ', 'age': 27 })

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2. Global and local variables

1 # global variable 2 school = 'lianhedaxue '3 4 def test (name ): 5 # force modify the global variable 6 global school 7 school = 'hahaha' 8 print ('before change', name, school) 9 name = 'jack' # This function is the scope of this variable 10 print ('after change', name) 11 12 name = 'Tom '13 test (name) 14 print (name) 15 print (school)

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3. recursive functions

Recursive Function. A function calls itself internally.

There must be a clear termination condition

Each time you enter a deeper layer of recursion, the problem scale should be reduced compared to the previous recursion.

Inefficient, too many recursive layers lead to Stack Overflow

1 def calc(n):2     print (n)3     if int(n/2) > 0:4         return calc(int(n/2))5     print ("->",n)6 calc(10)

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4. High-Order Functions

A variable can point to a function. If a function parameter can receive a variable, a function can receive another function as a parameter. This function becomes a high-order function.

1 def add(x,y,f):2     return f(x) + f(y)3 4 res = add (-1,2,abs)5 print (res)

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