python 入门基础知识练习

原创：叫我詹躲躲
链接：https://segmentfault.com/a/11...

1编写第一个程序,目前使用的都是python 3

# print('hello world!')

2.查看当前python编辑器的版本号

# python -v

3.使用变量

# message = 'hello world!'
# print(message)

4.字符串

name = 'jetty'
print(name.title()) #Jetty 首字母大写
print(name) # jetty
name.upper() #JEETY 转大写
name.lower() #jetty 转小写

5.合并拼接字符串

first_name = 'hongzhu'
last_name = 'zhan'
full_name = last_name +" "+ first_name
print(full_name) # zhan hongzhu

6.使用制表来添加空白

language = 'python\nJavascript\nC\nRust'
print(language)

# 打印
python
Javascript
C
Rust

7.删除空白

_blank = ' python '
print(_blank.rstrip()) #去除右侧空白
print(_blank.strip()) #去除两侧空白
print(_blank.lstrip()) #去除左侧空白

8.变量类型

num = 2.340
print(int(num)) # 整型 2
print(float(num)) # 浮点型 2.34

9.列表

color = ['red','green','yellow','pink']

# 访问元素
print(color[0]) #red

# 修改
color[0] = 'black'

# 添加元素
color.append('orange')

# 插入元素

color.insert(0,'blue') 插到第一位
print(color)

# 删除元素
del color[0] #删除当前元素

color.pop() # 删除数组最后一个元素

color.remove('red') # 删除红色

10 组织列表

排序列表

num_list = [1,2,3,4,2,1,3,1,2]
num_list.sort()
print(num_list) #[1, 1, 1, 2, 2, 2, 3, 3, 4]

临时排序

num_list = [1,2,3,4,2,1,3,1,2]
print(sorted(num_list)) #[1, 1, 1, 2, 2, 2, 3, 3, 4]

reverse 反序

num_list = [1,2,3,4,2,1,3,1,2]
num_list.reverse()
print(num_list) #[2, 1, 3, 1, 2, 4, 3, 2, 1]

列表的长度

num_list = [1,2,3,4,2,1,3,1,2]
print(len(num_list)) # 9

11 遍历列表

num_list = [1,2,3,4,2,1,3,1,2]
for i in num_list:
    print(i,end=" ") # 一行显示

12.使用函数遍历

num_list = [1,2,3,4,2,1,3,1,2]
for i in range(len(num_list)):
    print(num_list[i],end=" ")

13.乘方运算

squares = []
for i in range(1,6):
    squares.append(i**2)
print(squares) #[1, 4, 9, 16, 25]

14.内置函数

num_list = [1,2,3,4,2,1,3,1,2]
print(max(num_list)) #4
print(min(num_list)) #1
print(sum(num_list)) #19

15.列表解析

squeres = [value**2 for value in range(1,11)]
print(squeres) #[1, 4, 9, 16, 25, 36, 49, 64, 81, 100]

16.练习示例

16.1 1-50奇数的和

odd_number =[]
for i in range(1,11,2):
    odd_number.append(i)
print(sum(odd_number))

16.2 3-90 3的倍数

three_nmu = []
for i in range(3, 91):
    if (i % 3==0):
        three_nmu.append(i)
print(three_nmu)

16.3 1-10 的立方

squares = []
for i in range(3,11):
    squares.append(i**3)
print(squares)

16.4 1-10 的立方列表解析

squares = [i**3 for i in range(3,11)]
print(squares)

17 列表切片

num_list = [1,2,3,4,2,1,3,1,2]

print(num_list[0:5]) #[1, 2, 3, 4, 2] 从第一个开始取值到第五位
print(num_list[:5]) #[1, 2, 3, 4, 2] 默认会从第一个开始取值
print(num_list[5:]) #[1, 3, 1, 2] 取后面的4位

18 元组

dimensions = (100,300)
print(dimensions[0]) #100

for i in dimensions:
    print(i) #100 300

19 if 语句

num_list = [1, 2, 3, 4, 2, 1, 3, 1, 2]
for i in num_list:
    if i == 2:
        print(i)

20 !=

num_list = [1, 2, 3, 4, 2, 1, 3, 1, 2]
for i in num_list:
    if i != 2:
        print(i)

21 and

num_list = [1, 2, 3, 4, 2, 1, 3, 1, 2]
for i in num_list:
    if i >=1 and i <=2:
        print(i)

22 字典

alien  = {'color':0,'points':1}
print(alien['color']) #color

23 修改字典

alien  = {'color':0,'points':1}
alien['color'] = 'red'
print(alien) #{'color': 'red', 'points': 1}

24 删除字典

alien  = {'color':0,'points':1}
del alien['color']
print(alien)

25 案例练习

25.1创建两个人的字典，存储在列表，遍历列表，输出列表

people_nums1 = {'name':'jetty','name1':'jack'}
people_nums2 ={'name':'kitty','name1':'james'}
peoples = [people_nums1,people_nums2]
for i in peoples:
    print(i)

26.用户输入和while循环

ipt = input('你是小黄么？1(true) or 2(false)?')
if ipt =='1':
    print('是本人')
else:
    print('不是本人')

27 % //运算符

print(4 % 2)  # 0
print(4 // 2)  # 2

28 while运算符

count = 0
arr = []
while count < 20:
    for j in range(1, 100):
        if j % 11 == 0:
            count = count+1
            arr.append(j)
print(arr)

29 函数

# 简单求和
def num_sum(arr):
    result =0
    for i in arr:
        result =result+i
    return result

print(num_sum([1,2,3,4])) #10

30 函数默认值

def num_sum(arr=[1,2,3]):
    result =0
    for i in arr:
        result =result+i
    return result

print(num_sum()) #6

31 传递任意数量的实参

def make_prize(*top):
    return top

print(make_prize(1))
print(make_prize(1,2,3))
print(make_prize(1,3,4,5))
print(make_prize(1,1,1,1,1))

# 返回
(1,)
(1, 2, 3)
(1, 3, 4, 5)
(1, 1, 1, 1, 1)

32 导入函数

# 随机数
import random
print(random.randint(1,19))

33 类

class Dog():
    def __init__(self,name,age):
        self.name =name
        self.age = age

    def sit(self):
        print(self.name+''+self.age)

dog = Dog('jeety',24)
print(dog.name)

34 类 汽车里程表

class Car():
    def __init__(self,make,model,year):
        self.make = make
        self.model = model
        self.year = year

    def getCarName(self):
        print(self.model)

car = Car('audi','ad4',2016)
print(car.make)

35 子类方法 __init__()

class Car():
    def __init__(self,name):
        self.name = name

class Elastic(Car):
    def __init__(self, name):
        super().__init__(name)

myTesla = Elastic('tesla')
print(myTesla.name)

36 class实例

class Car():
    def __init__(self,make,name,color):
        self.make = make
        self.name = name
        self.color  = color

    def getCarName(self):
        print('获取车的名字为'+self.name+'获取汽车的颜色'+self.color)

class Batery():
    def __init__(self,batery='60'):
        self.batery = batery

    def discribe_batery(self):
        print('This car has'+str(self.batery)+'batery')

class Elatrity(Batery):
    def __init__(self, batery):
        super().__init__(batery)
        self.batery = Batery()

elatrity = Elatrity('100')
print(elatrity.discribe_batery())

37 文件和异常

f = open('file.txt',mode="w",encoding='utf-8')
print(f)
f.write('叫我詹躲躲\n')
f.write('叫我詹躲躲1\n')
f.close()

38 存储数据

将数据存入json文件

import json
numbers = [1,2,23,3,4,5,6,7,87]

filename = 'numbers.json'
with open(filename,'w') as f_obj:
    json.dump(numbers,f_obj)

39 保存和读取用户生成的数据

import json
username = input('存储输入的数据')

filename = 'numbers.json'
with open(filename,'w') as f_obj:
    json.dump(username,f_obj)

40 读取用户输入的信息

import json
filename = 'numbers.json'
with open(filename) as f_obj:
    username = json.load(f_obj)
    print('Welcome back',username)

41 输入和合并数据

import json
filename = 'numbers.json'
try:
    with open(filename) as f_obj:
        username = json.load(f_obj)
except FileNotFoundError:
    username = input('存储输入的数据')
    with open(filename,'w') as f_obj:
        json.dump(username,f_obj)
else:
    print('Welcome back',username)

42 封装成为一个函数

import json
def get_username():
    filename = 'numbers.json'
    try:
        with open(filename) as f_obj:
            username = json.load(f_obj)
    except FileNotFoundError:
        return None
    else:
        return username
def get_greeting():
    username = get_username()
    if username:
       print('Welcome back',username)
    else:
        username = input('存储输入的数据')
        filename = 'numbers.json'
        with open(filename,'w') as f_obj:
            json.dump(username,f_obj)
            print('Welcome back',username)

get_greeting()  

原创：叫我詹躲躲
链接：https://segmentfault.com/a/11...