python format函数用法详解：
1、位置
print("hello {0}, this is {1}.".format("world", "python")) # 根据位置下标进行填充
print("hello {}, this is {}.".format("world", "python")) # 根据顺序自动填充
print("hello {0}, this is {1}. {1} is a new language.".format("world", "python")) # 同一参数可以填充多次
输出：
hello world, this is python.
hello world, this is python.
hello world, this is python. python is a new language.
2、key
obj = "world"
name = "python"
print("hello {obj}, this is {name}.".format(obj = obj, name = name))
输出：
hello world, this is python.
3、列表
list = ["world", "python"]
print("hello {names[0]}, this is {names[1]}.".format(names = list))
输出：
hello world, this is python.
4、字典
dict = {"obj":"world", "name":"python"}
print("hello {names[obj]}, this is {names[name]}.".format(names = dict))
输出：
hello world, this is python.
注意：
访问字典的 key，不用引号。
5、类属性
class Names():
obj = "world"
name = "python"
print("hello {names.obj}, this is {names.name}.".format(names = Names))
输出：
hello world, this is python.
6、魔法参数
args = [",", "inx"]
kwargs = {"obj": "world", "name": "python"}
print("hello {obj}{} this is {name}.".format(*args, **kwargs))
输出：
hello world, this is python.
注意：
这里的 format(*args, **kwargs) 等价于 format(",", "inx", obj = "world", name = "python")。
二、数字格式化
三、其他用法
1、转义
print("{{hello}} {{{0}}}".format("world"))
输出：
{hello} {world}
2、format 作为函数变量
name = "python"
hello = "hello, welcome to {} world!".format
print(hello(name))
输出：
hello, welcome to python world!
3、格式化 datatime
from datetime import datetime
now = datetime.now()
print("{:%Y-%m-%d %X}".format(now))
输出：
2020-12-15 19:46:24
4、{}内嵌{}
print("hello {0:>{1}} ".format("world", 10))
输出：
hello world
