python3_基础

#!/usr/bin/python3
# -*- coding: utf-8 -*-

print("print practice-------------")
print("hello world")
#print(b"这是中文"）
print("I\'m ok")
print("-------------")
print(True and True)
print(True or False)
print(not False)
print("-------------")
#打印编码
print(ord('A'))
#print(ord('中'))
print("-------------")
print('\u4e2d\u6587')
print("ABC".encode("ascii"))
print("ABC".encode("utf-8"))
print("中文".encode('gb2312'))
print("-------------")
print("1.23e9: ",1.23e9)
print("name:%s,age:%d" % ("yifei",20))

print("list practice-------------")
print("list，列表，是一种有序的数据集合，可以随时添加删除其中的元素")
print("需要用[]包裹")
classmates = ["aaa","bbb","ccc"]
print("classmates:",classmates)
print("len:",len(classmates))
print("取倒数第n个,",classmates[-1],classmates[-2],classmates[-3])
classmates.append("ddd")
print("append element:",classmates)
classmates.insert(1,"jack")
print("insert element:",classmates)
classmates.pop()
print("delete last element:",classmates)
classmates.pop(3)
print("delete n\'th ele:",classmates)
classmates.append(["eee","fff"])
print("append a list:",classmates)

print("tuple practice-------------")
print("tuple,元组，也是有序列表，跟list非常像，但是一旦初始化就不能修改")
print("用()包裹")
t1=(1,2)
t2=()
print("t:",t1," t2:",t2)
t3=(3,)
print("定义只有一个元素的tuple，需要(3,) :",t3)
print("如果tuple里面包含list，那么其中的list是可以变的")
t=('a','b',['A','B'])
print("t:",t)
t[2][0]='X'
t[2][1]='Y'
print("t:",t)

print("if-------------")
age=20
if age>=18:
    print("adult")
elif age>=6:
    print("tennager")
else:
    print("kid")

print("input-------------")
birth="2009"
#birth=input("input birth:")
if birth > "2000":
    print("00后")
else:
    print("00前")
birth2=int(birth)
print(birth2)

print("cal list sum-------------")
sum=0
for x in [1,2,3,4,5,6,7,8,9,10]:
    sum=sum+x
print(sum)
print("list(range(5)):",list(range(5)))
sum=0
for x in range(101):
    sum=sum+x
print("0-100 sum:",sum)

print("while-------------")
sum=0
n=99
while n>0:
    sum=sum+n
    n=n-2
print(sum)

print("依次打印list-------------")
l=["tom","lisa","adam"]
for x in l:
    print("hello",x)

print("continue and break-------------")
sum2=0
nn=0
while True:
    if nn==5:
        nn=nn+1
        continue
    if nn>=10:
        break
    nn=nn+1
    sum2=sum2+nn
print(sum2)

print("dict-------------")
print("dict，字典，类似c++中的map，用{}包裹")
d={"daming":95,"bob":99}
print(d)
print("d[\"daming\"]:",d["daming"])
d["sam"]=100
print(d)
print("判断jack是否在dict中 \"jack\" in d:","jack" in d)
#使用get获取值，并可自定义key不存在时的返回值
d.get("daming")
d.get("ddd")
print(d.get("aaa",-1))
d.pop("daming")
print(d)

print("set-------------")
s=set([1,1,2,2,3])
print(s)
#增加元素
s.add(4)
print(s)
#移除元素
s.remove(1)
print(s)
#取交集并集
s2=set([3,4,5])
print(s & s2)
print(s | s2)

print("不可变对象-------------")
print("对不可变对象a调用replace，a不变")
a="abc"
b=a.replace('a','A')
print("a: ",a)
print("a:",a," b:",b)