📅  最后修改于: 2020-10-30 05:35:35             🧑  作者: Mango
Python next()函数用于从集合中获取下一个项目。它带有两个参数:迭代器和默认值,并返回一个元素。
此方法调用迭代器,如果不存在任何项目,则引发错误。为了避免错误,我们可以设置一个默认值。
该函数的签名在下面给出。
next (iterator[, default])
迭代器:它是一个迭代器对象。
默认值:如果元素不存在,则返回此值。
它从集合中返回一个项目。
让我们看一些next()函数的示例,以了解其功能。
在这里,我们使用next()函数获取项目。它不需要任何循环或索引。
# Python next() function example
number = iter([256, 32, 82]) # Creating iterator
# Calling function
item = next(number)
# Displaying result
print(item)
# second item
item = next(number)
print(item)
# third item
item = next(number)
print(item)
输出:
256
32
82
到达集合末尾时,此函数将引发错误。请参见下面的示例。
# Python next() function example
number = iter([256, 32, 82]) # Creating iterator
# Calling function
item = next(number)
# Displaying result
print(item)
# second item
item = next(number)
print(item)
# third item
item = next(number)
print(item)
# fourth item
item = next(number) # error, no item is present
print(item)
输出:
Traceback (most recent call last):
File "source_file.py", line 14, in
item = next(number)
StopIteration
256
32
82
# Python next() function example
number = iter([256, "javatpoint", 82,]) # Creating iterator
# Calling function
item = next(number)
# Displaying result
print(item)
# second item
item = next(number)
print(item)
# third item
item = next(number)
print(item)
# fourth item
item = next(number, "No item is present") # error, no item is present
print(item)
输出:
256
javatpoint
82
No item is present
在这里,我们设置一个默认值。现在,它不会引发任何错误,而是返回默认值。
# Python next() function example
number = iter([256, "javatpoint", 82,]) # Creating iterator
# Calling function
item = next(number)
# Displaying result
print(item)
# second item
item = next(number)
print(item)
# third item
item = next(number)
print(item)
# fourth item
item = next(number, "No item is left") # no error due to default value
print(item)
输出:
256
javatpoint
82
No item is left