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Introduction to Python string formatting methods

巴扎黑

Release： 2017-09-20 09:53:59

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This article mainly introduces Python string formatting methods (two methods). The editor thinks it is quite good. Now I will share it with you and give you a reference. Let’s follow the editor and take a look.

This article introduces Python string formatting. There are two main methods to share with you. The details are as follows

is used for splicing strings and has better performance. excellent.

There are two ways to format strings: percent sign method and format method.

The percent sign method is relatively old, while the format method is more advanced and attempts to replace the ancient method. Currently, the two coexist.

1. Percent sign method

Format: %[(name)][flags][width].[precision]typecode

(name) Optional, used to select the specified key
flags Optional, the available values are:

+ Right-aligned: Positive numbers are preceded by a positive sign, negative numbers are preceded by a minus sign
- Left-aligned: Positive numbers are preceded by no minus sign, and negative numbers are preceded by a minus sign

width Optional, occupying the width
.precision Optional, the number of digits retained after the decimal point
typecode Required

#s, get the return value of the __str__ method of the object passed in, and format it to the specified location
r, get the return value of the __repr__ method of the incoming object and format it to the specified location
c, integer: convert the number into its unicode corresponding value, the decimal range is 0 <= i <=1114111
o, convert the integer into octal representation, and format it to the specified location
x, convert integers to hexadecimal, and format them to the specified location
d, convert integers and floating point numbers It is expressed in decimal and formatted to the specified position

>>> s = &#39;i am %s,age %d&#39; %(&#39;cai&#39;,18)

>>> print(s)

i am cai,age 18

 

>>> s = &#39;i am %(n1)s,age %(n2)d&#39; %{&#39;n1&#39;:&#39;cai&#39;,&#39;n2&#39;:18}

>>> print(s)

i am cai,age 18

 

>>> s = &#39;i am %(n1)+10s,age %(n2)d&#39; %{&#39;n1&#39;:&#39;cai&#39;,&#39;n2&#39;:18}

>>> print(s)

i am    cai,age 18

 

>>> s = &#39;i am %(n1)+10s,age %(n2)10d&#39; %{&#39;n1&#39;:&#39;cai&#39;,&#39;n2&#39;:18}

>>> print(s)

i am    cai,age     18

 

>>> s = "i am %.3f abcd" %1.2

>>> print(s)

i am 1.200 abcd

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2, format mode,

i1 = "i am {},age {} ,{}".format(&#39;cairui&#39;,18,&#39;kk&#39;)
print(i1)
  i am cairui,age 18 ,kk
i1 = "i am {0},age {1} ,{0}".format(&#39;cairui&#39;,18)
print(i1)
  i am cairui,age 18 ,cairui
i1 = "i am {name},age {age} ,{name}".format(name=&#39;cairui&#39;,age=18)
print(i1)
  i am cairui,age 18 ,cairui
i1 = "i am {:s},age {:d} ,{:f}".format(&#39;cairui&#39;,18,6.1)
print(i1)
  i am cairui,age 18 ,6.100000

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