一、函数导入
1、为模块提供别名
>>> import math as foobar #设置math 别名为foobar
>>> foobar.sqrt(4)
显示：2.0
2、为函数提供别名
>>> from math import sqrt as foobar
>>> foobar(4)
显示：2.0
二、赋值
1、多值赋值
>>> x,y,z=1,2,3
>>> print(x,y,z)
显示：1,2,3
2、多值交换
>>> x,y=y,x
>>> print(x,y,z)
显示：2,1,3
3、增量赋值
>>> x=2
>>> x+=1
>>> x*=2
>>> x
显示：6
三、条件执行和if语句
1、if嵌套代码
>>> name=input('What is your name? ')
>>> if name.endswith('Gumby'):
>>> if name.startswith('Mr.'):
>>> print('Hello, Mr. Gumby')
>>> elif name.startswith('Mrs.')
>>> print('Hello, Mrs. Gumby')
>>> else:
>>> print('Hello, Gumby')
>>> else:
>>> print('Hello,stranger')
2、is,同一性运算符，和==相似，但事实上不一样
>>> x=y=[1,2,3]
>>> z=[1,2,3]
>>> x==y
显示：True
>>> x==z
显示：True
>>> x is y
显示：True
>>> x is z
显示：False
3、in，成员资格运算符
>>> if 's' in name:
>>> print('Your name contains the letter "s".')
>>> else:
>>> print('Your name does not contain the letter "s".')
4、assert,断言
>>>age=-1
>>> assert 0<age<100, 'The age must be realistic'
显示：AssertionError:The age must be realistic
5、while循环
>>> x=1
>>> while x<= 100:
>>> print(x)
>>> x+=1
6、for循环
>>> numbers=[0,1,2,3,4,5,6,7]
>>> for number in numbers:
>>> print(number)
7、循环遍历字典元素
>>> d={'x':1,'y':2,'z':3}
>>> for key in d
>>> print(key,'corresponds to',d[key])
显示： z corresponds to 1
>>> for key,value in d.items():
>>> print(key,'corresponds to',value)
8、并行迭代
>>> names=['anne','beth','george','damon']
>>> ages=[12,45,32,102]
>>> for i in range(len(names)):
>>> print(names[i],'is',ages[i],'years old')
采用内建zip来实现上述功能
>>> zip(names,ages)
>>> for name,age in zip(names,ages)
>>> print(name,'is',age,'years old')
9、翻转和排序迭代
>>> sorted([4,3,6,8,3]) #排序
显示：[3,3,4,6,8]
>>> sorted('Hello,world!')
显示：[' ','!',',','H','d','e','l','l','l','o','o','r','w']
>>> list(reversed('Hello,world!'))
显示：['!','d','l','r','o','w',' ',',','o','l','l','e','H']
>>> ' '.joing(reversed('Hello, world!'))
显示:'!dlrow,olleH'
10、跳出循环
>>> from math import sqrt
>>> for n in range(99,0,-1):
>>> root=sqrt(n)
>>> if root==int(root):
>>> print(n)
>>> break
显示：81
11、列表推导式，是利用其他列表创建新列表
>>> [x*x for x in range(10)]
显示：[0,1,4,9,16,25,36,49,64,91]
获取能被3整除的
>>> [x*x for x in range(10) if x % 3 ==0]
显示：[0,9,36,91]
更优推导式
>>> girls=['alice','bernice','clarice']
>>> boys=['charis','arnold','bob']
>>> letterGirls={}
>>> for girl in girls:
>>> letterGrils.setdefault(girl[0],[]).append(girl)
>>> print([b+'+'+g for b in boys for g in letterGirls[b[0]]])
显示：['charis+clarice','arnold+alice','bob+bernice']
12、占位
>>> if name=='Ralph Auldus Melish':
>>> print('Welcome!')
>>> elif name=='Enid':
>>> pass #占位
>>> elif name=='Bill Gates':
>>> print('Access Denied')
13、exec执行
>>> from math import sqrt
>>> scope={}
>>> exec('sqrt=1',scope)
>>> sqrt(4)
显示：2
>>> scope['sqrt']
显示：1
14、eval用于求值
>>> eval(input('Enter an arithmetic expression: '))
Enter an arithmetic expression: 6+18*2
显示：42