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Introduction to the usage of * in python (code example)

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2019-03-09 13:48:322477browse

This article brings you an introduction to the usage of * in python (code examples). It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

1. Represents multiplication operation

2. Represents multiples

def T(msg,time=1):
    print((msg+' ')*time)

T('hi',3)

Result: hi hi hi

3. Single*

3.1 The

*parameter that appears in the formal parameter position of a function definition is used to accept any number of parameters and put them in a tuple.

def demo(*p):
    print(p)
    
demo(1,2,3)

Result: (1, 2, 3)

3.2 Appears in the actual parameter position of the function call

When the function calls multiple parameters, it appears in the list or tuple , collections, dictionaries and other iterable objects as actual parameters, and add * in front, the interpreter will automatically unpack and pass to multiple single-variable parameters (the number of parsed parameters must be equal to the number of function parameters) .

a=[1,2,3]
d(*a)

Result: 1 2 3

4. Two ** appear in the formal parameter part of the function definition

For example: **parameter is used to receive keys similar to Put multiple actual parameters in the same assignment form as parameters into the dictionary (that is, convert the parameters of the function into a dictionary).

def demo(**p):
    for i in p.items():
        print(i)
       
demo(x=1,y=2)

Result: ('x', 1) ('y', 2)

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