python 中字符串格式化函数 format()

001、

>>> "{0}".format("xxx")                         ## 位置参数
'xxx'
>>> "{0}.{1}.{2}".format("xxx", "yyy", "zzz")
'xxx.yyy.zzz'
>>> "\t{0}.{1}.{2}".format("xxx", "yyy", "zzz")
'\txxx.yyy.zzz'
>>> "{0}.\n{1}.{2}".format("xxx", "yyy", "zzz")
'xxx.\nyyy.zzz'
>>> print("{0}.\n{1}.{2}".format("xxx", "yyy", "zzz"))
xxx.
yyy.zzz

002、

>>> "{a}.{b}.{c}".format(a = "aaa", b = "bbb", c = "ccc")        ## 关键字参数
'aaa.bbb.ccc'
>>> "{a}.{b}.{c}".format(a = "ccc", b = "bbb", c = "aaaa")
'ccc.bbb.aaaa'
>>> "\t{a}.{b}.{c}".format(a = "ccc", b = "bbb", c = "aaaa")
'\tccc.bbb.aaaa'
>>> print("\t{a}.{b}.{c}".format(a = "ccc", b = "bbb", c = "aaaa"))
        ccc.bbb.aaaa

当同时出现位置参数和关键字参数时， 位置参数应写在关键字参数的前面。