【Python】列表 List ③ ( 查询操作 / 修改操作 | 列表查询操作 List#index | 修改列表指定位置元素值 )

列表变量.index(数据元素)

    def index(self, *args, **kwargs): # real signature unknown
        """
        Return first index of value.
        返回值的第一个索引。
        
        Raises ValueError if the value is not present.
        如果值不存在则引发ValueError。
        """
        pass

"""
列表 List 常用操作 代码示例
"""

# 定义列表
names = ["Tom", "Jerry", "Jack", "Tom"]

print(names.index("Tom"))

0

"""
列表 List 常用操作 代码示例
"""

# 定义列表
names = ["Tom", "Jerry", "Jack", "Tom"]

print(names.index("Hello"))

Y:\002_WorkSpace\PycharmProjects\pythonProject\venv\Scripts\python.exe Y:/002_WorkSpace/PycharmProjects/HelloPython/hello.py
Traceback (most recent call last):
  File "Y:\002_WorkSpace\PycharmProjects\HelloPython\hello.py", line 8, in <module>
    print(names.index("Hello"))
ValueError: 'Hello' is not in list

Process finished with exit code 1

Traceback (most recent call last):
  File "Y:\002_WorkSpace\PycharmProjects\HelloPython\hello.py", line 9, in <module>
    print(names.index("Hello"))
ValueError: 'Hello' is not in list

列表变量[下标索引] = 新的元素值

"""
列表 List 常用操作 代码示例
"""

# 定义列表
names = ["Tom", "Jerry", "Jack"]

print(names)

# 使用正向索引修改列表指定元素
names[1] = "Tom"

print(names)

# 使用反向索引修改列表指定元素
names[-1] = "Jerry"

print(names)

['Tom', 'Jerry', 'Jack']
['Tom', 'Tom', 'Jack']
['Tom', 'Tom', 'Jerry']