Python Learning--functions__python

Preface:

This section describes how to customize functions, call functions, and use functions in function libraries

1. Custom Function

A, Format: def + function name (parameters):

def hello_world (word):

Note that there are colon colons: B, optional function annotations

"" "Prints ' Hello world! ' to the console." "

C, Function body

Word = "Hello world!"
Print (word)

Organize the above code as follows:

def hello_world (word): "" "
	prints ' Hello world! ' to the console.
	" " Word = "Hello world!"
	Print (word)

Note: In order to be aesthetically pleasing, the annotation and function body should be distinguished from the function definition line, that is, by using a space indent

2, Call function function name (parameter)

HelloWorld ("I Love python!")

3. function Call FunctionIn line with C + +, call another function directly inside the function

def cube (number): Return
    number*number*number

def by_three (number):
    if (number% 3) = = 0: return
        Cube ( Number)
    else: return
        False

4. module function LibraryImport Module
For example, to use the Math function library, you need to add the import math before the program

Import Math
print math.sqrt
#输入结果为5

The above only uses the mean square function, but uses the MATH.SQRT () the longer expression, appears verbose.
You can use the From module import function, the From math import sqrt, to simplify the invocation expression, that is, sqrt ().

From math import sqrt
print sqrt (25)

5, Universal ImportsTo make it easy to invoke functions in a function library, you can add the From module import * expression
To invoke all functions in the Math function library, you can use the following program code

From Math Import *

6, built-in functions

def biggest_number (*args):
    print max (args) return
    max (args)
    
def smallest_number (*args):
    print min ( args) return
    min (args)

def distance_from_zero (ARG):
    print ABS (ARG) return
    ABS (ARG)


Biggest_ Number ( -10, -5, 5,)
Smallest_number ( -10, -5, 5, ten)
Distance_from_zero (-10)

Function Analysis:
Max ()--Returns the maximum value in a set of integer or floating-point values

Maximum = max (1,2,3,8.8,9.9,4,7,6,9)

print maximum

Min ()--Returns the minimum value in a set of integer or floating-point values

Minimum = min (1,2,3,0.5)

Print minimum

ABS ()--Returns the absolute value of the input value

Absolute = ABS ( -99)

Print Absolute

Type ()--Returns the types of data

Print type        #int
print type (99.9)      #float
Print type (' Python ')  #str

These functions are all built-in functions, that is, you do not need to add a function library

7, ReviewIf/elif/else

def  Shut_down (s):
    if s = = "Yes": Return
        "shutting down"
    elif s = = "No": Return
        "Shutdown aborted" C12/>else: Return
        "Sorry"

Modules

Import Math
Print math.sqrt (13689) #结果是117.0

Built-in functions

def distance_from_zero (number):
    if Type (number) = int or type (number) = = float: return
        ABS (number)
    else : Return
        "Nope"

8, actual combat program--taking a vacation8.1 Planning Your Trip

def hotel_cost (nights): Return
    140*nights

8.2 Getting There

def plane_ride_cost (city):
    if City = = "Charlotte": Return
        183
    elif City = = "Tampa": Return
    elif City = = "Pittsburgh": Return
        222
    elif City = = "Los Angeles": Return
        475

8.3 Transportation

def rental_car_cost (days):
    If->= 7: Return
        days*40-50
    elif days >= 3: Return
        days*40-20 return
    days*40

8.4 Together

def hotel_cost (nights): Return
    140*nights
    
def plane_ride_cost (city):
    if City = = "Charlotte":
        return 183
    elif City = = "Tampa": Return
    elif city = "Pittsburgh": Return
        222
    elif city = "Los Angeles": Return
        475
    
def rental_car_cost (days):
    if >= 7: Return
        days*40-50
    elif days >= 4/>return days*40-20 return
    days*40
    

def trip_cost (city,days): Return
    Hotel_cost (days) + Plane_ride_ Cost (city) + Rental_car_cost (days)

8.5 plan Your tripsWhat if we went to Los Angeles for 5-and-brought-extra-dollars-money?

def hotel_cost (nights): Return
    140*nights
    
def plane_ride_cost (city):
    if City = = "Charlotte":
        return 183
    elif City = = "Tampa": Return
    elif city = "Pittsburgh": Return
        222
    elif city = "Los Angeles": Return
        475
    
def rental_car_cost (days):
    if >= 7: Return
        days*40-50
    elif days >= 4/>return days*40-20 return
    days*40
    

def trip_cost (City,days,spending_money): Return
    Hotel_cost (days + plane_ride_cost (city) + rental_car_cost (days) + Spending_money
    
print ("Above costs%d dollars!"% trip_cost ("Los A Ngeles ", 5, 600))