python format()函数的使用技巧

1. 替换字符串中的占位符：

name = "Alice"
age = 30
message = "My name is {} and I am {} years old.".format(name, age)
print(message)

2. 指定占位符的顺序：

name = "Alice"
age = 30
message = "My name is {1} and I am {0} years old.".format(age, name)
print(message)

3. 格式化数字的显示：

num = 123.456789
formatted_num = "{:.2f}".format(num)
print(formatted_num)  # 输出：123.46

4. 格式化日期时间：

from datetime import datetime
now = datetime.now()
formatted_date = now.strftime("%Y-%m-%d %H:%M:%S")
print(formatted_date)

5. 使用键值对替换占位符：

person = {"name": "Alice", "age": 30}
message = "My name is {name} and I am {age} years old.".format(**person)
print(message)

6. 使用列表替换占位符：

items = ["apple", "banana", "cherry"]
message = "I like {} and {} and {}.".format(*items)
print(message)