Python's Way (ii) function

Python functions

1. def defines function keywords;

2. Function name, call the function by function name later;

3. function declaration, not automatic execution;

4. Parameters of the function;

5. Return value of the function;

return value:

1. The return value is not explicitly specified and returns none;

2. The return value can be assigned to a variable;

3. The return value can be a variable or a data structure.

Number of arguments:

1. Formal parameters

2. Actual parameters

3. Function can define multiple parameters

Default parameters:

1. Do not pass, the default value is used;

2. Pass the parameter, overriding the default value.

Dynamic Parameters:

1. Receive multiple parameters, when transmitting the sequence;

2. Internal automatic construction of the Yuan zu;

3. Sequence, *, avoid the internal automatic construction of the progenitor.

Define the format of the function:

def function name ():

function content; function content

function content; function content

function name () # Execute function

# 1. Implement the function Len function to take string length

a= "Hellomyteacher"

print Len (a)

# 2. Implement the cut split function for a string

a= "Student"

B=a.split ("U")

Print B

C:\Python27\python.exe "e:/python-file/learn-python.py"

[' st ', ' Dent ']

Process finished with exit code 0

# Custom Functions

def A ():

print "Hello";p rint 777

A ()

C:\Python27\python.exe "e:/python-file/learn-python.py"

Hello

777

Process finished with exit code 0

function is implemented by Reuturn to let function return worthwhile function

The return value of a function has three cases:

1. A case of a return value

def test ():

i=7

return I

Print test ()

2. A variable stores multiple return value-assigned cases

def test2 (i,j):

K=i*j

return (i,j,k)

X=test2 (4,5)

Print X

C:\Python27\python.exe "e:/python-file/learn-python.py"

(4, 5, 20)

Process finished with exit code 0

3. Scenarios where multiple variables store multiple return values

def test3 (i,j):

K=i*j

return (i,j,k)

X,y,z=test3 (4,5)

Print X

Print Y

Print Z

C:\Python27\python.exe "e:/python-file/learn-python.py"

4

5

20

Process finished with exit code 0

Default parameters:

Def show (args,arg1= ' a '):

Print (ARGS,ARG1)

Print (ARGS,ARG1)

Show (12,arg1= ' 1 ')

Show (12)

12 1

12 1

A

A

Dynamic Parameters:

1)

Def show (*args,**kwargs):

Print (Args,type (args))

Print (Kwargs,type (Kwargs))

Show (12,34,a=1,b=2)

<class ' tuple ' >

{' A ': 1, ' B ': 2} <class ' Dict ' >

2)

>>> def Show (*args,**kwargs):

.. print (Args,type (args))

.. print (Kwargs,type (Kwargs))

...

>>> i = [11,22,33]

>>> v = {' K2 ': 1, ' K1 ': 2}

>>> Show (i,v)

([One, all,], {' K2 ': 1, ' K1 ': 2}) <class ' tuple ' >

{} <class ' dict ' >

>>> Show (*i,**v)

(One, one, one) <class ' tuple ' >

{' K2 ': 1, ' K1 ': 2} <class ' Dict ' >

3)

>>> test = ' name: {0}, pwd: {1} '

>>> test.format (' Lihongye ', ' pwd1 ')

' Name:lihongye, Pwd:pwd1 '

>>> test = ' name: {x}, pwd: {y} '

>>> Test.format (x= ' Lihongye ', y= ' pwd1 ')

' Name:lihongye, Pwd:pwd1 '

>>> test_dic = {' x ': ' Lihongye ', ' y ': ' Pwd1 '}

>>> Test.format (**test_dic)

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Python path (ii) function