### 不同类型的 Python f-string 格式化符号及其用法 #### 表达式的嵌入 f-string允许直接在字符串中嵌入表达式，这些表达式会被计算并替换为其结果。表达式可以是变量名或者更复杂的表达式。 ```python name = "Alice" age = 30 print(f"My name is {name} and I am {age} years old.") ``` #### 数字格式化 对于数值数据，可以通过指定格式说明符来控制输出的形式： - 浮点数保留两位小数：`{variable:.2f}` - 整数以二进制表示：`{variable:b}` - 科学计数法显示浮点数：`{variable:e}` 或 `{variable:E}` (大写E) ```python pi = 3.141592653589793 binary_number = 10 scientific_notation = 123456789.0 print(f"Pi rounded to two decimal places: {pi:.2f}") # Pi rounded to two decimal places: 3.14[^3] print(f"The binary representation of 10 is: {binary_number:b}") # The binary representation of 10 is: 1010 print(f"In scientific notation, this number looks like: {scientific_notation:e}") # In scientific notation, this number looks like: 1.234568e+08 ``` #### 对齐方式 通过使用 `<`, `>`, 和 `^` 符号可以在固定宽度的空间内左对齐、右对齐或居中文本。 ```python text_left_aligned = 'left' text_right_aligned = 'right' centered_text = 'middle' print(f'Left aligned text within width=10: |{text_left_aligned:<10}|') # Left aligned text within width=10: |left | print(f'Right aligned text within width=10: |{text_right_aligned:>10}|') # Right aligned text within width=10: | right| print(f'Centered text within width=10: |{centered_text:^10}|') # Centered text within width=10: | middle | ``` #### 字符串填充字符 除了默认的空白填充外，还可以自定义其他字符作为填充物，只需将其放在冒号后面即可。 ```python filled_string = 'hello' padding_char = '*' print(f'{filled_string:*<10}') # hello***** print(f'{filled_string:*>10}') # *****hello print(f'{filled_string:*^10}') # **hello*** ``` #### 调用对象的方法和属性 可以直接调用对象的方法以及访问其属性来进行格式化操作。 ```python class Person: def __init__(self, first_name, last_name): self.first_name = first_name self.last_name = last_name @property def full_name(self): return f"{self.first_name} {self.last_name}" person = Person('John', 'Doe') print(f'The person\'s full name is {person.full_name}.') # The person's full name is John Doe. ```