字典

s = {}
print(s,type(s))

字典：k v 键值对的形式存在的

s = {
    'linux':[100,99,89],
    'python':[90,99,100]
    }
print(s,type(s))

工厂函数

d = dict()
print(d,type(d))
d = dict(a=1,b=2)
print(d,type(d))

字典的嵌套

student = {
    123:{
        'name':'tom',
        'age':18,
        'score':99
          },
    456:{
        'name':'lily',
        'age':18,
        'score':89
    }
 }
print(student)
print(student[123]['score'])

字典的特性

d = {
    '1':'a',
    '2':'b'
}
print(d['1'])

字典不支持切片
成员操作符针对的是key

print('1' in d)
print('a' in d)

for循环针对的是key

for key in d:
    print(key)

遍历字典

for key in d:
    print(key,d[key])

字典元素的添加

service = {
    'http':80,
    'ftp':23,
    'ssh':22
}

增加一个元素：如果key值存在则更新对应的value，如果key不存在则添加对应的value

service['https'] = 443
print(service)
service['ftp'] = 21
print(service)

service_backup = {
   'tomcat':8080,
    'mysql':3306
}

service.update(service_backup)
print(service)
service.update(dns=53)
print(service)

如果key值存在则不做修改，如果key值不存在则添加对应的值

service.setdefault('http',9090)
print(service)
service.setdefault('oracle',44575)
print(service)

字典元素的删除

service = {
    'http':80,
    'ftp':23,
    'ssh':22
}

pop删除指定的key对应的value值

item = service.pop('http')
print(item)
print(service)

删除最后一个k-v (k,v)

a = service.popitem()
print(a)
print(service)

清空字典内容

service.clear()
print(service)

字典元素的查看

service = {
    'http':80,
    'ftp':23,
    'ssh':22
}

查看字典中所有的key值

print(service.keys())

查看字典中所有的value值

print(service.values())

查看字典中的k-v

print(service.items())

练习

在这里插入图片描述

来源：CSDN

作者：Aa. NiceMan

链接：https://blog.csdn.net/AaNiceMan/article/details/103616453

标签

python遍历字典

service