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Python语法

#输出
print("dlkjfs");
a=10
age=18;
print("sdfs %d dlfj"%age);
print("dfj%s %s"%("小张","dfjd"))

print("aaa","bbb","kkk")
print("www","baidu","com",sep=".")

print("hello",end="")
print("hello",end="\t")
print("hello",end="\n")

'''
'''
#输入
password= input("dlfj")
print("lsdjf",password)

a=input("lsdjfs")
print(type(a))
a=int("123")
int()#强制类型转化
b=a+100
print(b)

'''
'''
#判断
if True:
    print("ldjf")
else :
    print("fjdslf")
import random
x=random.randint(0,2)#随机数
print(x)

#循环
for i in range(5):
    print(i);
for i in range(0,14,3):#从0开始到13结束
    print(i)

name="chengdu"
for x in name:
    print(x,end=' ')

a=["aa","bb","cc"]
for i in range(len(a)):
    print(a[i])

i=0
while i<5:
    print("当前第几次%d"%(i+1))
    print("i=%d"%i)#注意是百分号
    i+=1

i=1
sum=0
while i<=100:
    sum+=i;
    i+=1
print(sum)

count=10
while count<5:
    print(count,"xiaoyu5")
    count+=1
else:
    print(count,"大于或对于5")
    break
    continue

for i in range(1,10,1):
    print(\t)
    for j in range(1,i+1,1):
        print(%d*%d=%d %(i,j,i*j),end=\t)

for x in range(1, 10):
    print(\t)
    for y in range(1, x + 1):
                result = x * y
                print( % d * % d = % d % (x, y, x * y), end =\t)


for m in range(1,10):
    for n in range(1,10):
        if m n:
            print(%s*%s=%s%(m,n,m*n),end= \t)
        elif m == n:
            print(%s*%s=%s%(m,n,m*n),end=\n)

for i in range(1, 10, 1):
    for j in range(1, i + 1, 1):
        print("%d*%d=%d" % (j, i, i * j), end=" ")
    print('\t')

#字符串
word ='字符串'
sentence ="sehsdfsdf"
paragraph="""sdfjlsdfjs
dsfsdljkf
"""
print(word)
print(sentence)
print(paragraph)

my_str='dlfj\'d'
print(my_str)

my_str="Jason sair\"dsf\""
print(my_str)
str="chengdu"
print(str)
print(str[0:5])
print(str[1:7:2])#起始位置：结束位置：步进值
print(str[1:])
print(str[:5])
print(str*10+",dkjfd"*3)
print(r"hello\ndfdf")#r能取消\号效果

namelist=[545,"xdjfkd","小李"]
#print(type(namelist[0]))

for i in namelist:
    print(type(len(namelist)))

i=0
while i<len(namelist):
    print(namelist[i])
    i+=1

#增
for name in namelist:
    print(name)
nametemp=input()
namelist.append(nametemp)

for name in namelist:
    print(name)

a=[1,2]
b=[3,4]
a.append(b)#将列表当作一个元素
print(a)

a.extend(b)
print(a)#将b列表元素，全部加入

a=[0,1,2]
a.insert(1,3)  #第一个是下标，第二个是元素
print(a)

#删
m=["1111","2222","3333","4444","5555"]
for i in m:
    print(i)
del m[2]
m.pop()
m.remove("1111")#只删除第一个
for i in m:
    print(i)

#改
m=["1111","2222","3333","4444","5555"]
for i in m:
    print(i)
print("-------------------")
m[1]="xioahong"

for i in m:
    print(i)

#查
m=["1111","2222","3333","4444","5555"]
findname=input()

if findname in m:
    print("找打")
else :
    print("没有")

a=["a","b","c","a","b"]
#print(a.index("a",0,4))#可以查找指定下标范围元素，返回指定下标(范围区间为左闭右开) 找不到报错
print(a.count("a"))


#排序
a=[1,4,2,3]
print(a)
a.reverse()
print(a)
a.sort(reverse=True)
print(a)

import  random
s =[["a","b"],["c","d"],["e","f"]]
print(s[0][0])
for name in s:
    index=random.randint(0,2)
    s[index].append(name)
for a in s:
    print()


#元组
t=("sdf","kldsf",2020,2021,333)
t2=(50,)
print(t[0:5])#左闭右开

#增(连接)
t=(12,23,34,45)
t2=("ldfj","ldsjf")
t=t+t2
print(t)

#删
t=(12,23,34)
print(t)
del tup
print(t)

#字典 dict
a={"name":"dkfj","age":18}#定义
print(a["age"])
print(a.get("sdlfj"))#没有找到返回none（默认）
print(a.get("dsfj","hhh"))
print(a.get("age","20"))

#增
a={"name":"dkfj","age":18}#定义
newID=input()
a["id"]=newID
print(a["id"])

#删
a={"name":"dkfj","age":18}#定义
print("%s"%a["name"]+"a"*10)
del a["name"]

a={"name":"dkfj","age":18}#定义
print("%s"%a)
#del a
#claer 清空
a.clear()
print(a)

#改
a={"name":"dkfj","age":18}#定义
a["age"]=1223
print(a["age"])

#查(遍历)
a={"name":"wang","age":18}#定义
print(a.keys())
print(a.values())
print(a.items())

for key in  a.keys():
    print(key)
for value,key in a.items():
    print("%s  %s"%(key,value))

mylist=["a","c","b"]
print(enumerate(mylist))
#使用枚举函数同时拿到下标内容
for i,x in enumerate(mylist):
    print(i,x)

#集合set
#去重

#函数
def printa():
    print("-"*10)
    print("test")
    print("-"*10)

#printa()
def add2Num(a,b):
    c=a+b
    print(c)
add2Num(11,22)

def add2Num(a,b):
    return a+b

res=add2Num(11,22)
print(res)

def divid(a,b):
    shang=a//b
    yushu=a%b
    return shang,yushu
sh,yu=divid(5,2)   #多个返回值
print("%d  %d"%(sh,yu));

a=100
def test1():
    global a#global
    a=300
    print(a)

def test2():
    a=200
    print(a)

test1()
test2()
print(a)

#文件
f=open("test.txt","w")#打开文件
f.close()  #关闭文件

f=open("test.txt","w")
f.write("lsdjfkdsljfs")
f.close()
#读取指定的字符，开始读头部，往后依次读
f=open("test.txt","r")#打开文件
c=f.read(5)
print(c)
c1=f.read(5)
print(c1)

f.close()

f=open("test.txt","r")#打开文件
c=f.readlines(); #一次性读取全部列表
print(c)
i=1
for t in c:
    print("%d:%s"%(i,t))
    i+=1
f.close()

import os
os.rename("test01.txt","test.txt")

#异常
#捕获异常
try:
    #print("-test"*10)
    f=open("123.txt","r");
    print(name)
    print("-"*10)#不会执行
except (NameError,IOError,SyntaxError)as result:
    print("错误")         #捕获异常执行代码
    print(result)


try:
    #print("-test"*10)
    f=open("123.txt","r");
    print(name)
    print("-"*10)#不会执行
except Exception as result:
    print("错误")         #捕获异常执行代码
    print(result)

# try finally 和嵌套
import time

try:
    f = open("test.txt", "r")
    try:
        while True:
            c = f.readline()
            if (len(c)) == 0:
                break
            time.sleep(2)
            print(c)
    finally:
        f.close()
        print("文件关闭")

except Exception as result:
    print("发生异常")