py中字典的增加

services = {
    'http':80,
    'ftp':21,
    'mysql':3306
}

#增加一个元素
#如果key值存在，则更新对应的value值
#如果key值不存在，添加key-value值对

services['ssh'] = 22
print(services)
services['http'] = 443
print(services)

#添加多个key-value值

services_backup = {
    'https':443,
    'tomcat':8080,
    'ssh':22
}

services.update(services_backup)
print(services)

services.update(flask=9000,http=8000)
print(services)

#setdefault添加key值
#如果key值存在，不做修改
#如果key值不存在，添加对应的key-value

services.setdefault('http',9090)
print(services)

services.setdefault('oracle',44575)
print(services)