Python如何使用f-string和str.format()进行字符串操作及格式化？

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文章目录前言概述常用字符串操作format() 方法字符串格式化操作f-stringf-string 例子format('sp')

文章目录

• ​​preface​​

• ​​[overview]​​
• ​​常用字符串操作​​
• ​​format()方法 字符串格式化操作​​
• ​​f-string 字符串​​

• ​​f-string​​
• ​​f-string examples:​​
• ​​format specifiers​​
• ​​Raw f-string​​

preface

• 到目前位置,我认为python的字符串插值语法在诸多现代编程语言中是最为方便的,允许你在字符串中直接使用​​{}​​​来指明一个表达式,而统一地将指示该字符串是一个插值字符串的​​f​​提到字符串的前面
• python 提供了两种现代化的字符串格式化方法:format()和f-string

• 前者的风格更像正则表达式分组中的操作
• 后者更加简单,内联替换变量名为字符串,阅读起来更加方便

[overview]

​​overview​​​​docs.python.org/zh-cn/3/library/string.html#format-string-syntax​​

​​目录​​

• ​​string​​ — 常见的字符串操作

• ​​字符串常量​​
• ​​自定义字符串格式化​​

常用字符串操作

• ​​string — 常见的字符串操作 ​​

format()方法 字符串格式化操作

• ​​内置类型str.format — Python 文档​​
• ​​PEP 3101 – Advanced String Formatting | peps.python.org​​

f-string 字符串

• 格式字符串语法

• ​​格式规格迷你语言​​
• ​​格式示例​​

• ​​模板字符串​​
• ​​辅助函数​​

f-string

​​www.python.org/dev/peps/pep-0498/​​

• a f-string looks like:
  ​​​f ' <text> { <expression> <optional !s, !r, or !a> <optional : format specifier> } <text> ... '​​

---

• Python supports multiple ways to format text strings.
• These include​​%-formatting​​​ [​​1]​​​,​​str.format()​​​ [​​2]​​​, and​​string.Template​​​ [​​3]​​.
• Each of these methods have their advantages, but in addition have disadvantages that make them cumbersome to use in practice.
• This PEP proposed to add a new string formatting mechanism: Literal String Interpolation. In this PEP, such strings will be referred to as “f-strings”, taken from the leading character used to denote such strings, and standing for “formatted strings”.

f-string examples:

import datetime
name = 'Fred'
age = 50
anniversary = datetime.date(1991, 10, 12)
# example1:
f'My name is {name}, my age next year is {age+1}, my anniversary is {anniversary:%A, %B %d, %Y}.'
>>> 'My name is Fred, my age next year is 51, my anniversary is Saturday, October 12, 1991.'
# example2:
f'He said his name is {name!r}.'
>>>"He said his name is 'Fred'."

format specifiers

​​www.python.org/dev/peps/pep-0498/#id30​​​

Raw f-string

​​www.python.org/dev/peps/pep-0498/#id43​​