python 表达式和语句及for、while循环练习实例

2024-02-16 18:13:02 167

Python中表达式和语句及for、while循环练习

1)表达式

常用的表达式操作符：
x+y,x-y
x*y,x/y,x//y,x%y

逻辑运算：
xory,xandy,notx

成员关系运算：
xiny,xnotiny

对象实例测试：
xisy,xnotisy

比较运算：
xy,x<=y,x>=y,x==y,x!=y

位运算：
x|y,x&y,x^y,x<>y

一元运算：
-x,+x,~x:

幂运算：
x**y

索引和分片：
x[i],x[i:j],x[i:j:stride]

调用：
x(...)

取属性：
x.attribute

元组：(...)
序列：[...]
字典：{...}

三元选择表达式：xifyelsez

匿名函数：lambdaargs:expression

生成器函数发送协议：yieldx

运算优先级：
(...),[...],{...}
s[i],s[i:j]
s.attribute
s(...)
+x,-x,~x
x**y
*,/,//,%
+,-
<<,>>
&
^
|
<,<=,>,>=,==,!=
is,notis
in,notin
not
and
or
lambda

2)语句：

赋值语句

调用
print：打印对象
if/elif/else:条件判断
for/else:序列迭代
while/else:普通循环
pass:占位符
break:
continue
def
return
yield
global:命名空间
raise:触发异常
import:
from:模块属性访问
class:类
try/except/finally:捕捉异常
del:删除引用
assert:调试检查
with/as:环境管理器

赋值语句：

隐式赋值：import,from,def,class,for,函数参数

元组和列表分解赋值：当赋值符号(=)的左侧为元组或列表时，Python会按照位置把右边的对象和左边的目标自左而右逐一进行配对儿；个数不同时会触发异常，此时可以切片的方式进行；

多重目标赋值

增强赋值:+=,-=,*=,/=,//=,%=,

3)for循环练习

练习1：逐一分开显示指定字典d1中的所有元素，类似如下
k1v1
k2v2
...

>>>d1={'x':1,'y':2,'z':3,'m':4}
>>>for(k,v)ind1.items():
printk,v
y2
x1
z3
m4

练习2：逐一显示列表中l1=["Sun","Mon","Tue","Wed","Thu","Fri","Sat"]中的索引为奇数的元素；

>>>l1=["Sun","Mon","Tue","Wed","Thu","Fri","Sat"]
>>>foriinrange(1,len(l1),2):
printl1[i]

Mon
Wed
Fri

练习3：将属于列表l1=["Sun","Mon","Tue","Wed","Thu","Fri","Sat"]，但不属于列表l2=["Sun","Mon","Tue","Thu","Sat"]的所有元素定义为一个新列表l3;

>>>l1=["Sun","Mon","Tue","Wed","Thu","Fri","Sat"]
>>>l2=["Sun","Mon","Tue","Thu","Sat"]
>>>l3=[]
>>>foriinl1:
ifinotinl2:
l3.append(i)
>>>l3
['Wed','Fri']

练习4：已知列表namelist=['stu1','stu2','stu3','stu4','stu5','stu6','stu7']，删除列表removelist=['stu3','stu7','stu9']；请将属于removelist列表中的每个元素从namelist中移除(属于removelist，但不属于namelist的忽略即可)；

>>>namelist=['stu1','stu2','stu3','stu4','stu5','stu6','stu7']
>>>removelist=['stu3','stu7','stu9']
>>>foriinnamelist:
ifiinremovelist:
namelist.remove(i)
>>>namelist
['stu1','stu2','stu4','stu5','stu6']

4)while循环练习

练习1：逐一显示指定列表中的所有元素；

>>>l1=[1,2,3,4,5]
>>>i=0
>>>whilei>>l1=[1,2,3,4,5]
>>>whilel1:
printl1.pop(0)

1
2
3
4
5

练习2：求100以内所有偶数之和；

>>>i=0
>>>sum=0
>>>whilei<101:
sum+=i
i+=2
printsum

2550

>>>foriinrange(0,101,2):
sum+=i
printsum

2550

练习3：逐一显示指定字典的所有键；并于显示结束后说明总键数；

>>>d1={'x':1,'y':23,'z':78}
>>>i1=d1.keys()
>>>whilei1:
printi1.pop(0)
else:
printlen(d1)
x
y
z
3

练习4：创建一个包含了100以内所有奇数的列表；

>>>d1=[]
>>>i=1
>>>whilei<101:
d1.append(i)
i+=2
>>>printd1
[1,3,5,7,9,11,13,15,17,19,21,23,25,27,29,31,33,35,37,39,41,43,45,47,49,51,53,55,57,59,61,63,65,67,69,71,73,75,77,79,81,83,85,87,89,91,93,95,97,99]

>>>d1=[]
>>>foriinrange(1,101,2)
d1.append(i)
>>>printd1
[1,3,5,7,9,11,13,15,17,19,21,23,25,27,29,31,33,35,37,39,41,43,45,47,49,51,53,55,57,59,61,63,65,67,69,71,73,75,77,79,81,83,85,87,89,91,93,95,97,99]

练习5：列表l1=[0,1,2,3,4,5,6],列表l2=["Sun","Mon","Tue","Wed","Thu","Fri","Sat"]，以第一个列表中的元素为键，以第二个列表中的元素为值生成字典d1；

>>>l1=[0,1,2,3,4,5,6]
>>>l2=["Sun","Mon","Tue","Wed","Thu","Fri","Sat"]
>>>d1={}
>>>count=0
>>>iflen(l1)==len(l2):
whilecount
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python 表达式和语句及for、while循环练习实例

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