format怎么用python

在Python中，`format（）`方法用于格式化字符串，它允许你将变量值插入到字符串中的占位符位置。以下是`format（）`方法的基本用法：

基本格式化

```python

name = "Alice"

age = 25

message = "My name is {} and I am {} years old."

print（message.format（name, age）） 输出：My name is Alice and I am 25 years old

指定位置
```python
name = "Alice"
age = 25
print（"My name is {0}, and I am {1} years old."
print（message.format（name, age）） 输出：My name is Alice, and I am 25 years old

使用关键字参数

```python

name = "Alice"

age = 25

print（"My name is {name}, and I am {age} years old."

print（message.format（name=name, age=age）） 输出：My name is Alice, and I am 25 years old

格式说明符
```python
value = 3.
formatted_value = "Value: {:.2f}".format（value） 输出：Value: 3.14

填充和对齐

```python

name = "Alice"

age = 25

print（"Name: {:<10}, Age: {:>5}".format（name, age）） 输出：Name: Alice , Age: 25

列表和字典
```python
a_list = ["chuhao", 20, "china"]
print（"My name is {0}, from {0}, age is {0}".format（a_list）） 输出：My name is chuhao, from china, age is 20
b_dict = {"name": "chuhao", "age": 20}
print（"Name: {name}, Age: {age}".format（b_dict）） 输出：Name: chuhao, Age: 20

以上示例展示了`format（）`方法在Python中的多种用法，包括位置指定、关键字参数、格式说明符以及列表和字典的格式化。