字典的使用

## 访问一个元素

```python

# 第一种方法

dict_1 = {"name":"刘烽吉","age":21,"sex":"男"}

print(dict_1['name'])

# 第二种

print(dict_1.get("name"))

```

## 增加

```python

dict_1 = {"name":"刘烽吉","age":21,"sex":"男"}

dict_1['id']=1

```

## 删除元素

```python

dict_1 = {"name":"刘烽吉","age":21,"sex":"男"}

del dict_1['name']

dict_1.pop('name')
print(dict_1)

# 删除所有元素

dict_1.clear()

print(dict_1)

```

## 修改

```python

dict_1 = {"name":"刘烽吉","age":21,"sex":"男"}

dict_1.update('{name':"aa"})

# update 更新操作，有该键话就会修改，无该键的话就会新建

```

 

```python

dict_1 = {"1101":"北京市","1201":"天津市","1301":"河北省石家庄市","1401":"山西省太原市"}
for key, value in dict_1.items():
    print(key,value)
dict_1["1501"] = "内蒙古呼和浩特市"
print(dict_1)
num_1 = input("请输入你想删除的省市编码")
dict_1.pop(num_1)
print(dict_1)
num_2 = input("请输入你要修改的省市编码")
num_3 = input("请输入修改后的编码")
num_4 = input("请输入修改后的省市")
dict_1.pop(num_2)
dict_1[num_3] = num_4
print(dict_1)
num_5 = input("请输入想要查询省市的编码")
print(dict_1.get(num_5))



# 两个序列之间的操作

sum = 0
list_2 = list(input("请输入一个序列"))
for i in list_2:
    if i == ",":
        list_2.remove(i)
print(list_2)
for j in list_2:
    sum +=int(j)
print(sum)
list_1 = list(input("请输入一个序列"))
for n in list_1:
    if n in list_2:
        print("%s在原来的列表中"%n)

# 判断闰年

def panduan(num_4):
    if num_4%400 ==0 or num_4%4==0 and num_4%100!=0:
        return "为闰年"
    else:
        return "不是闰年"

if __name__ == '__main__':
    nianfen = int(input("请输入年份："))
    print(panduan(nianfen))


#反转字符串

str = input("请输入一段字符串")
print(str[::-1])

#注册登录功能

list_1 = []
import random
def print_info():
    print("1.注册")
    print("2.登录")
    print("3.退出")


def zhuce_1():
    global dict_1
    i = ""
    while len(i)<6:
        j = random.randint(1,9)
        j = str(j)
        i += j
    dict_2 = {}
    num_3 = input("请输入您的密码:")
    print("您的账号是%s" % i)
    print("您的密码是%s" % num_3)
    dict_2["账号"] = i
    dict_2["密码"] = num_3
    list_1.append(dict_2)

def denflu():
    zhanghao_1 = input("请输入账号：")
    miam = input("请输入密码：")
    if {"账号":zhanghao_1,"密码":miam} in list_1:
        print("登陆成功")
    else:
        print("登录失败")


while 1:
    print_info()
    num_1 = input("请输入你要执行的操作")
    if num_1 == "1":
        zhuce_1()
    elif num_1 == "2":
        denflu()
    elif num_1 == "3":
        num_2 = input("你确定要退出吗？ y or n")
        if num_2 == "y":
            break
        elif num_2 == "n":
            continue
        else:
            print("输入错误")


# 三角形

for i in range(6):
    print(i*"*")
for j in range(10,1,-1):
    print(j*'*')

# 九九乘法表

for i in range(10):
    for j in range(i):
        print("%d*%d=%d\t"%(j+1,i,((j+1)*i)),end='')
    print()
# 四则运算

def size(a,b,fuhao):
    if fuhao == "+":
        return a+b
    elif fuhao == "-":
        return a-b
    elif fuhao == '*':
        return a*b
    elif fuhao == "/":
        return a/b
    else:
        print("gun")

if __name__ == '__main__':
    a = int(input('请输入一个数字'))
    b = int(input('请输入一个数字'))
    fuhao = input('请输入符号')
    print(size(a,b,fuhao))

```