What does python string formatting mean?

Python string formatting means using the format function to format a string.

Usage: It uses {} and: to replace the traditional % method.

1. Use positional parameters

Key points: From the following example, we can see that positional parameters are not subject to order constraints and can be {}, as long as there are corresponding parameter values ​​in the format. The parameter index starts from 0, and the incoming positional parameter list can be *list

>>> 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'

2. Use keyword parameters

Key points: the keyword parameter values ​​must match, and a dictionary can be used as a keyword parameter To pass in the value, just add ** in front of the dictionary

>>> 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. Filling and formatting

:[Filling character][Alignment] [Width]

>>> '{0:*>10}'.format(10)  ##右对齐
'********10'
>>> &#39;{0:*<10}&#39;.format(10)  ##左对齐
&#39;10********&#39;
>>> &#39;{0:*^10}&#39;.format(10)  ##居中对齐
&#39;****10****&#39;

4. Precision and base

>>> '{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'

5. Using index

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

Related tutorial recommendations: Python video tutorial

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