python系列文章目录
python基础(01变量&数据类型&运算符)
python基础(02序列共性)
python基础(03列表和元组)
python基础(04字符串&字典)
python基础(05集合set)
文章目录
前言
持续学习,争取早日退休!
一、语句块
缩进
二、bool类型:Ture、False
1、False:none、0、“”、()、[]、{}
>>> bool('')
False
2、true:1、其他
>>> bool('hello')
True
3、可以相加
>>> True + False + 42
43//false代表0 true 代表1
三、条件判断(if、else、elif)
1.if
a = int(input('pls enter the number:'))
if a > 2:
print 'bigger than 2'
2.else
a = int(input('pls enter the number:'))
if a > 2:
print 'bigger than 2'
else:
print 'not bigger than 2'
3.elif
a = int(input('pls enter the number:'))
if a > 2:
print 'bigger than 2'
elif a < 2:
print 'not bigger than 2'
else:
print 'a ==2'
4.嵌套语句块
name = input("pls enter the name:")
if name.endswith('z'):
if name.startswith('m'):
print 'hello m'
elif name.startswith('l'):
print 'hello l'
else:
print'z'
else:
print 'hello stranger'
5.if-else新用法(类似三元运算符)
>>> a,b = 1,2
>>> c = 'more' if a>b else 'less'
>>> print(c)
less
------------------------------------------>>
>>> c = {True:'more',False:'less'}[a>b]
>>> c
'less'
6.运算符
x==y
x<y
x>y
x<=y
x>=y
x !=y
x is y
x is not y
x in y
x not in y
and
or
not:取反
四、循环语句
1.while循环
x = 0
while x <=100:
print(x)
x += 1
2.for循环(可以为一个可迭代对象的每一个元素执行一个语句块)
nums = [0,1,2,3,4,5,6,7,8,9]
for num in nums:
print(num)
3.循环遍历字典元素
1、遍历键(默认)
d = {'x':1,'y':2,'z':3}
for key in d:
print(key,'is',d[key])
2、遍历值
d = {'x':1,'y':2,'z':3,'a':11}
for value in d.values():
print(value)
3、遍历键值
d = {'x':1,'y':2,'z':3,'a':11}
for key,value in d.items():
print(key,value)
4.跳出循环
1、break
2、continue
5.for中的else语句
注意:for 能正常结束,或者 continue 也没事,都会执⾏ else 语句块,只有当for 循环 触发 break 了, else 不会执⾏
num=【'a','b','c'】
for i in num:
print(1)
else:
print("ccc")
----------------------------------->>
1
1
1
ccc
------------------------------------>>
num=['a','b','c']
for i in num:
print(1)
continue
else:
print("ccc")
----------------------------------->>
1
1
1
ccc
-------------------------------------->>
num=['a','b','c']
for i in num:
print(1)
break
else:
print("ccc")
---------------------------------------->>
1
五、推导式
1.列表推导式
代码如下(示例):
>>> c = [i+1 for i in a]
>>> c
[2, 3, 4]
--------------------------------
>>> d = [i+1 for i in a if i % 2 > 0]
>>> d
[2, 4]
------------------------------------
>>> def fun(i):
return i*2
>>> e = [fun(i) for i in a if i % 2 > 0]
>>> e
[2, 6]
2.字典推导式
代码如下(示例):
a='anbxncbhdwgwjavcbdhjd'
b={i:a.count(i) for i in a}
print(b)
2.集合推导式
代码如下(示例):
print({x for x in range(1,100) if x%9==0})
总结
理解即可!
标签:语句,06,推导,python,else,num,print From: https://blog.csdn.net/m0_55605424/article/details/141299509