实例

检查列表中是否存在 "banana"：

fruits = ["apple", "banana", "cherry"]
if "banana" in fruits:
  print("yes")

完整实例：

fruits = ["apple", "banana", "cherry"]
if "banana" in fruits:
  print("yes")

定义和用法

in 关键字有两种作用：

in 关键字用于检查序列（列表、范围、字符串等）中是否存在值。

in 关键字还用于在 for 循环中迭代序列：

实例

遍历列表并打印项目：

fruits = ["apple", "banana", "cherry"]
for x in fruits:
  print(x)

完整实例：

fruits = ["apple", "banana", "cherry"]
for x in fruits:
  print(x)