How can the starting position be specified in Python?

In Python, you can specify the starting position using slices.

The syntax for slicing is [start:stop:step]. Start refers to the index from which to begin, defaulting to 0, or the first element. Stop indicates the index at which to end, defaulting to the length of the list. Step represents the interval for each value to be taken, defaulting to 1.

Here are a few examples:

1. Obtain a sublist starting from the second element to the last element in the list.

my_list = [1, 2, 3, 4, 5]
sub_list = my_list[1:]
print(sub_list)  # 输出 [2, 3, 4, 5]

1. Extract a substring starting from the third character to the last character in the given string.

my_string = "Hello, world!"
sub_string = my_string[2:]
print(sub_string)  # 输出 "llo, world!"

1. Create a sublist by selecting every other element starting from the first element in the list.

my_list = [1, 2, 3, 4, 5]
sub_list = my_list[::2]
print(sub_list)  # 输出 [1, 3, 5]

Note that slicing does not modify the original list or string, but instead creates a new sublist or substring.