这篇文章主要介绍了python 字符串格式化的示例，帮助大家更好的理解和使用python处理字符串，感兴趣的朋友可以了解下
一、旧式的字符串格式化
% 操作符
参考以下示例：
>>> name = "Eric" >>> "Hello, %s." % name 'Hello, Eric.'
当有多个变量需要插入到字符串中时：
>>> name = "Eric" >>> age = 74 >>> "Hello, %s. You are %s." % (name, age) 'Hello, Eric. You are 74.'
当需要替换的变量进一步增多时，使用 % 操作符格式化字符串会导致代码可读性变得很差：
>>> first_name = "Eric" >>> last_name = "Idle" >>> age = 74 >>> profession = "comedian" >>> affiliation = "Monty Python" >>> "Hello, %s %s. You are %s. You are a %s. You were a member of %s." % (first_name, last_name, age, profession, affiliation) 'Hello, Eric Idle. You are 74. You are a comedian. You were a member of Monty Python.'
str.format()
str.format() 是对 % 方式的改进，它使用常见的函数调用的语法，并且可以通过定义对象本身的 __format__() 方法控制字符串格式化的具体行为。
基本用法：
>>> name = "Eric" >>> age = 74 >>> "Hello, {}. You are {}.".format(name, age) 'Hello, Eric. You are 74.'str.format() 相对于 % 操作符有着更强的灵活性。比如可以通过数字索引来关联替换到字符串中的变量：
>>> name = "Eric" >>> age = 74 >>> "Hello, {1}. You are {0}.".format(age, name) 'Hello, Eric. You are 74.'为了提高代码可读性，{} 中也可以使用有具体含义的参数名：
>>> name = "Eric" >>> age = 74 >>> "Hello, {name}. You are {age}".format(name=name, age=age) 'Hello, Eric. You are 74'针对字典结构的数据：
>>> person = {'name': 'Eric', 'age': 74} >>> "Hello, {name}. You are {age}.".format(name=person['name'], age=person['age']) 'Hello, Eric. You are 74.'或者更简洁的方式：
>>> person = {'name': 'Eric', 'age': 74} >>> "Hello, {name}. You are {age}.".format(**person) 'Hello, Eric. You are 74.'问题在于当需要替换的变量很多时，str.format() 方式依然会导致代码变得过于冗长：
>>> first_name = "Eric" >>> last_name = "Idle" >>> age = 74 >>> profession = "comedian" >>> affiliation = "Monty Python" >>> "Hello, {first_name} {last_name}. You are {age}. \ You are a {profession}. You were a member of {affiliation}."\ .format(first_name=first_name, last_name=last_name, age=age, \ profession=profession, affiliation=affiliation) 'Hello, Eric Idle. You are 74. You are a comedian. You were a member of Monty Python.' 二、f-string
基本用法
>>> name = "Eric" >>> age = 74 >>> f"Hello, {name}. You are {age}." 'Hello, Eric. You are 74.'嵌入表达式
>>> f"{2 * 37}" '74' >>> def to_lowercase(input): ... return input.lower() >>> name = "Eric Idle" >>> f"{to_lowercase(name)} is funny" 'eric idle is funny' >>> f"{name.lower()} is funny" 'eric idle is funny'f-string 中还可以直接嵌入某个对象实例，只要其内部实现了 __str__ 或者 __repr__ 方法：
class Comedian: def __init__(self, first_name, last_name, age): self.first_name = first_name self.last_name = last_name self.age = age def __str__(self): return f"{self.first_name} {self.last_name} is {self.age}" new_comedian = Comedian("Eric", "Idle", 74) print(f"{new_comedian}") # Eric Idle is 74多行 f-string
>>> name = "Eric" >>> profession = "comedian" >>> affiliation = "Monty Python" >>> message = ( ... f"Hi {name}. " ... f"You are a {profession}. " ... f"You were in {affiliation}." ... ) >>> message 'Hi Eric. You are a comedian. You were in Monty Python.'参考资料
Python 3's f-Strings: An Improved String Formatting Syntax (Guide)
以上就是python 字符串格式化的示例的详细内容，更多关于python 字符串格式化的资料请关注html中文网其它相关文章！
以上就是python 字符串格式化的示例的详细内容，更多请关注0133技术站其它相关文章！
