Python string formatting

There are two ways to format strings in Python3:% and format

One,%

Place a string on the left side of the% operator that needs to be formatted, with one or more embedded translation targets, beginning with%, such as%s,%d,%f.

Place an object to the right of the% operator, which will be inserted on the left side where you want Python to format the string as a translation destination.

Case:

>>> ' This is a%s '% ' test ' "This is a test ' >>>>>> ' Shuangji%d.this is a%s '% (666, ' Test ') #右侧有多个值时用括号括起来 ' Shuangji 666.this is a test ' >>>>>> '%s--%s--%s '% (666,231.51241,[1,2,3]) # Any type in Python can be converted to a string. The left side of the instance is%s, and the object in the right is converted to a string (re-created). ' 666--231.51241--[1, 2, 3] ' >>>

% left common structure is%[(name)][flags][width width][.precision precision]typecode,-left alignment, + sign, 0 complement 0

>>> x=1234>>> test= '%d...%-6d...%06d '% (x,x,x)        The   #-is left-aligned. 0 Insufficient digits 0 >>> test ' 1234 ... 1234 &NBSP, ..... 001234 ' >>> x=12.126435787654123                      #浮点数的表示方法 >>>  '%e|%f|%g '% (x,x,x) ' 1.212644e+01|12.126436|12.1264 ' >>>  '%-6.2f|%0 6.2f|%+06.1f '% (x,x,x)              #6.2 indicates a total of 6 digits, 2 decimal places ' 12.13 |012.13|+012.1 ' >>>  '%-6.2f|%0 6.2f|%.*f '% (x,x,4,x)              #此处 * Indicates accuracy, 4 to * after X is the alternative value ' 12.13 |012.13|12.1264 ' >>>>>>  '% (a) s % (b) s % (c) s % (d) s '  %   ({' A ': ' This ', ' B ': ' Is ', ' C ': ' A ', ' d ': ' Test '})          #基于字典的格式化, is to use a key value. ' This is a test '

Second, Format method

>>>  ' this {} a {} '. Format (' is ', ' test ')               #默认1对1, 1 more, 1 not ' this is a test ' >>>  ' this {1}  a {0} '. Format (' is ', ' test ')             # {} Locate the replacement target and insert the parameter ' this test a is ' >>>  ' this {x} a {y} ' by location. Format (x= ' Is ', y= ' test ')             #{} to find the replacement target and insert parameters by keyword ' this  is a test ' >>>  ' this {x} a {0} '. Format (' is ', x= ' test ')               #两者都有 ' This test a is ' >>> >>>  ' This {1[spam]} test of {0.platform} '. Format (sys,{' spam ': ' Is '})       #0表示第一个位置,.platform  represents the object properties referenced by the location or keyword: sys.platform. ' This is test of linux ' >>>

The

Format format structure {Fieldname!conversionflag:formatspec},fieldname represents a numeric position or keyword for the parameter, Conversionflag can be r,s,a corresponding repr/str/ One invocation of the ASCII built-in function, Formatspec specifies how the value is represented: field width, alignment, fill 0, decimal precision, and so on. The Formatspec form after the colon is: [[fill]align alignment][sign][#][0][width width][.precision precision][typecode]

>>> ' {0:>10}={1:<10} '. Format (' Test ', 12.62424) #字段宽度为10个,> right-aligned,< left-aligned ' test=12.62424 ' >&G T;> import sys>>> ' {0.platform:>10}={1[item]:<10} '. Format (sys,dict (item= ' laptop ')) # Use the location. Property method to replace the value ' linux=laptop ' >>>>>> ' {0:.2f} '. Format (1/3.0) ' 0.33 ' >>> ' {0:.{ 1}F} '. Format (1/3.0,4) #动态的从参数列表获取精度位数 ' 0.3333 ' >>> ' {%.*f} '% (6,1/3.0) #动态的使用% get precision digits from the argument list ' {0.333333} ' & Gt;>>

Advanced usage

        >>> msg= ' This {a} a {b} for  PYTHON,THE NO.{C} '. Format (**{' A ': ' Is ', ' B ': ' A ', ' C ': 1})               #使用字典形式来格式化, you must add two  * numbers and braces          >>> print (msg)         this is a a  for python,the no.1        >>>         >>> msg= ' this {:s} a {:s} for python,the  no.{:d} '. Format (' is ', ' test ', 1)                          >>> print (msg)          this is a test for python,the no.1      &nbSp;  >>>        >>> msg= ' this {: s} a {:s} for python,the no.{:d} '. Format (*[' is ', ' test ', 1])               #列表形式加入一个 *, * indicates that the elements in the list are traversed, similar to the one in the preceding column          >>> print (msg)         this  Is a test for python,the no.1        >> >

Python string formatting