python基础

# age =12
# if age>=18:
#     print('adult')
# else:
#     print('teenager')

# x=10
# x+=3
# print(x)

#输出
# name=input()
# print(name)

#常量
# PI=3.1415926359

# n=123
# f=456.789
# s1='Hellow,World'
# s2='Hello,\'Admin\''
# s3=r'Hello,"Bart"'
# s4=r'''Hello,
# Lisa!'''
# print(
#     s1,
#     s3,
#     f//n
#     )

#list 用[]中括号定义
# classmates=['Michael','Bob','Tracy']
# print(classmates[0])
# print(len(classmates))

#取最后
# print(classmates[-1])

#插入
# classmates=['Michael','Bob','Tracy']
# classmates.append('Admin')
# print(classmates)

# 指定位置插入
# classmates=['Michael','Bob','Tracy']
# classmates.insert(1,'Jack')
# print(classmates)

# 删除指定位置的元素
# classmates=['Michael','Bob','Tracy']
# classmates.pop(1)
# print(classmates)

# 元素替换
# classmates=['Michael','Bob','Tracy']
# classmates[0]='abc'
# print(classmates)

# 里面的元素的数据类型也可以不同
# A=['Apple',123,True]
# print(A)

# Tuple元组用（）括号定义,和list有序列表基本一致，但是没有 insert pop append等方法，取值同样通过下标索引

# t=(1,2)
# print(t[-1])

# 空元组
# t=()
# print(len(t))


# 定义一个数值的元组加个 ,逗号（区别list有序列表）
# t=(1,)
# print(len(t)) 1
# print(t[0]) 1

# a指向‘abc’,b=a，指向a，a重新指向xyz，b不改变指向
# a='abc'
# b=a
# a="xyz"
# print(b) abc


# L = [
#     ['Apple', 'Google', 'Microsoft'],
#     ['Java', 'Python', 'Ruby', 'PHP'],
#     ['Adam', 'Bart', 'Lisa']
# ]
# print(L[0][0]) Apple

函数：

# def myFun(a):
#     if(a<0):
#         return -a
#     else:
#         return a  一定有返回值

# print(myFun(-6))

# 定义空函数 pass作用：占位
# def ab(ab):
#     pass 
# print(ab(-1)) None

# 位置参数
# def power(x, n):
#     s = 1
#     while n > 0:
#         n = n - 1
#         s = s * x
#     return s
# print(power(5,2))

# 默认参数
# def add_end(L=None):
#     if L is None:
#         L=[]
#     L.append("END")
#     return L

# print(add_end())
# print(add_end())
# print(add_end())

# 可变参数
# def variable(number):
#     sum=0
#     for x in number:
#         sum=sum+x*x
#     return sum
# print(variable([1,2,3]))

# def variable(*number):
#     sum=0
#     for x in number:
#         sum=sum+x*x
#     return sum
# print(variable(1,2,3))