python中字符串的format操作

1、使用位置参数

要点：从以下例子可以看出位置参数不受顺序约束，且可以为{},只要format里有相对应的参数值即可,参数索引从0开，传入位置参数列表可用*列表

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li = [‘hoho’,18]
‘my name is {} ,age {}’.format(‘hoho’,18)
‘my name is hoho ,age 18’
‘my name is {1} ,age {0}’.format(10,’hoho’)
‘my name is hoho ,age 10’
‘my name is {1} ,age {0} {1}’.format(10,’hoho’)
‘my name is hoho ,age 10 hoho’
‘my name is {} ,age {}’.format(*li)
‘my name is hoho ,age 18’
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2、使用关键字参数

要点：关键字参数值要对得上，可用字典当关键字参数传入值，字典前加**即可

hash = {‘name’:’hoho’,’age’:18}
‘my name is {name},age is {age}’.format(name=’hoho’,age=19)
‘my name is hoho,age is 19’
‘my name is {name},age is {age}’.format(**hash)
‘my name is hoho,age is 18’

3、填充与格式化

:[填充字符][对齐方式 <^>][宽度]

‘{0:*>10}’.format(10) ##右对齐
‘********10’
‘{0:*<10}’.format(10) ##左对齐
‘10********’
‘{0:*^10}’.format(10) ##居中对齐
‘*10*’

4、精度与进制

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‘{0:.2f}’.format(1/3)
‘0.33’
‘{0:b}’.format(10) #二进制
‘1010’
‘{0:o}’.format(10) #八进制
‘12’
‘{0:x}’.format(10) #16进制
‘a’
‘{:,}’.format(12369132698) #千分位格式化
‘12,369,132,698’
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5、使用索引

li
[‘hoho’, 18]
‘name is {0[0]} age is {0[1]}’.format(li)
‘name is hoho age is 18