Functions of Python (ii)

First, the function related concepts

1. Global variables: Outside the function, the variable defined above is the global variable

2. Local variables: defined in the function, can not be used after the function, if you want to modify the value of the global variable in the function, you need to add the keyword global before the function, but the dictionary and list of the variable variable, do not need to use

Global has declared that it can be changed directly.

3. A few examples of parameters:

A. Variable parameter, parameter group-tuple form:

def send_mail (*args):

Print (args)

Send_mail (' [email protected] ', ' [email protected] ', ' [email protected] ')

B. Variable parameters, parameter groups-dictionary form:

def send_mail (**kwargs):

Print (Kwargs)

Send_mail (k1= ' v1 ', k2= ' v2 ')

Ii. recursion of functions

1. Function calls itself, up to 999 cycles

2. In the case of recursion, there must be a definite end condition

3. Example:

Def my2 ():
   num = input (' Enter a number: ')
   num = int (num)
   If num%2!=0:
      Print (' Please enter an even number ')
      Return My2 ()
My2 ()

Iii. list derivation, List-generation

1. Example:

Import Random
res = [26, 7, 18, 27, 32, 28]
For I in range (len (res)):
   Res[i] = str (res[i]). Zfill (2)
#列表推导式, List-generated
Res1 = [Str (i). Zfill (2) for I in res]--equivalent to the for loop above
Print (RES1)
Res2 = [i+10 for i in Res]
Print (Res2)
HH = [I for I in Range (0,1001,2)]
Print (HH)

Iv. built-in functions

1.max (range (1,28))--MAX, run result: 27

2.min (Range (28))-Minimum, run result: 0

3.sum (range (1,101))--summing, running result: 5050

4.res = sorted ([2,3,1,2,3],reverse=true)--Sort, plus reverse=true is in descending order

5.res = eval ('--eval '), execute Python code, execute simple Python code only

6.F = open (' Code ', encoding= ' utf-8 ') code = F.read () exec (code)---exec, Python code executable in the file

7.sql = ' INSERT into My_user value ({id},{name},{addr},{sex},{phone}) '

Sql.format (name= ' aaa ', addr= ' sdfsfd ', sex= ' xxx ', id=11)--format function is a function of formatting a string

8. For index,s in Enumerate (stus): The print (index,s)--enumerate () function is used to combine a traversed data object (such as a list, tuple, or string) into an index sequence, listing both data and data subscripts, typically used in For Loop, the enumerate (enum) object is returned, and if the subscript start position is written as 1, the enumeration object is returned from ordinal 1.

9.for Name,se,ag in Zip (stus,sex,age):p rint (NAME,SE,AG)-Multiple lists compressed together

Functions of Python (ii)