一、例子：

"_".join(["1","2","3","4"])"_".join(map(lambda x:str(x),[1,2,3,4]))"{0}-{1}".format(3.4,34)"{}-{}-{}".format(3,4,5)"{name}-{age}".format(**{
   'name':'song','age':34})"{name}-{age}".format(name='song',age=34)"the list first is: {obj[0]}".format(obj=[1,2,3,4])"the list first is: {0[0]},{0[1]}".format([1,2,3,4])"{:>8}".format('abc')"{0:<8}".format('abc')"{0:_<8}".format('abc')"{0:0>8}".format('3.14')"{0:.2f}".format(123.123456)"{0:b}".format(1023)"{0:d}".format(0b1111111111)"{0:x}".format(1023)"{0:,}".format(102345.6789)

 

二、结果：

>>> "_".join(["1","2","3","4"])'1_2_3_4'>>> "_".join(map(lambda x:str(x),[1,2,3,4]))'1_2_3_4'>>> "{0}-{1}".format(3.4,34)'3.4-34'>>> "{}-{}-{}".format(3,4,5)'3-4-5'>>> "{name}-{age}".format(**{
   'name':'song','age':34})'song-34'>>> "{name}-{age}".format(name='song',age=34)'song-34'>>> "the list first is: {obj[0]}".format(obj=[1,2,3,4])'the list first is: 1'>>> "the list first is: {0[0]},{0[1]}".format([1,2,3,4])'the list first is: 1,2'>>> "{:>8}".format('abc')'     abc'>>> "{0:<8}".format('abc')'abc     '>>> "{0:_<8}".format('abc')'abc_____'>>> "{0:0>8}".format('3.14')'00003.14'>>> "{0:.2f}".format(123.123456)'123.12'>>> "{0:b}".format(1023)'1111111111'>>> "{0:d}".format(0b1111111111)'1023'>>> "{0:x}".format(1023)'3ff'>>> "{0:,}".format(102345.6789)'102,345.6789'>>>