python It is a very practical technology , Today, I'd like to briefly introduce python The function in .
First , Function is an integration of algorithms , Easy to be called in multiple places .
Two ： Fixed format of function ：、
The function is displayed according to the specific algorithm , But there is a fixed format ;、
deffun_name( var):
# Specific algorithm
return result
The result given to the caller after the function finishes execution
return, As long as the implementation of the return This call to the function will be stopped
1. If the function doesn't write return, no return value . What was received was None
2. Yes return. return It doesn't write anything or return The back is None. return None
3.return A value . Return a result
Parameters : Information passed to the function when the function is called
Shape parameter : Variables in the position of the function declaration
Actual parameters : The specific value given in the function call
The ginseng : A procedure that assigns an argument to a formal parameter during a function call .
Actual parameters :
1. Positional arguments . Pass information to formal parameters by position
2. Key parameters . Pass information to the parameter according to the name of the parameter
3. Mixing parameters . First position, then keyword
Shape parameter :
1. Positional arguments
2. Default parameter , Must be written after the position parameter
3. Dynamic parameters
for example :
1 The determinants of arguments :
1. # Assign values to formal parameters according to their positions
def food(breakfast,lunch,dinner):
print(" I want to eat ",breakfast,lunch,dinner)
food(" milk "," The steak "," Apple ") # I want to eat milk The steak Apple
2. Assign a value to the parameter according to its name
def food(breakfast,lunch,dinner):
print(" I want to eat ",breakfast,lunch,dinner)
food(breakfast=" milk ",lunch=" The steak ",dinner=" Apple ")# I want to eat milk The steak Apple
2 List of formal parameters :
Declare parameters by position , Just like arguments
def information(name,age,sex):
print(name,age,sex)
information(" Xiaohong ","29"," Woman ")
information(" Xiaomei ","1"," Woman ")
information(" Xiao Ming ","29"," male ")
information(" aunt ","43"," Woman ")
When passing values to parameters , No value given , Default values work . Make sure you have at least one value to use . Give a worthy word , The default value does not work . The order : The position parameter must be placed first . The default value parameter must be placed later .
def information(name,age,sex=" Woman "):
print(name,age,sex)
information(" Xiaohong ","29",)
information(" Xiaomei ","1",)
information(" Xiao Ming ","29"," male ")
information(" aunt ","43",)
The result at this time is similar to 1 The results of the position parameters are consistent , Use for input that is consistent in most cases , Special separate treatment is enough .
Dynamic parameters , Used when parameters are uncertain .
def fun (*args)
fun(args)
The Works of Liezi 1. If the parameters are uncertain , The following list , Each person eats differently , Different kinds of food , In this case, dynamic parameter transfer is used .
def fun(*food):
#* It represents an indefinite parameter , You can pass any message , The parameter name is still food, And the received information is Yuanzu ()
print(" I want to eat ",food)
fun(" meat ") #* Represents the dynamic transfer of position parameters As a result, I want to eat ( meat ',)
fun(" Steamed Rice "," Spicy strips "," instant noodles ")# I want to eat (' Steamed Rice ', ' Spicy strips ', ' instant noodles ')
The Works of Liezi 2. The dynamic parameter must be after the position parameter .
def fun (*fruit,a,b):
print(" I want to eat ",fruit,a,b)
fun(" Apple "," pears "," Banana ") # At this time, the program will report an error , All by food To receive the ,a and b Never receive parameters .
def fun (a,b,*fruit):
print(" I want to eat ",a,b,fruit)
fun(" Mango. "," pears "," Banana "," The oranges ") # I want to eat Mango. pears (' Banana ', ' The oranges ')
All right. , I'll introduce you here today , Continue another day .
