python中next()方法用法详解

源码解析：

def next(iterator, default=None): # real signature unknown; restored from __doc__
    """
    next(iterator[, default])
    
    Return the next item from the iterator. If default is given and the iterator
    is exhausted, it is returned instead of raising StopIteration.
    """
    pass

python中next()的具体的形式为：next(iterobject,defalt)

• 第一个参数是可迭代的对象
• 第二个参数可以写也可以不写，不写的时候，如果可迭代的元素取出完毕，会返回StopIteration异常，第二个参数写的时候，当可迭代对象迭代完后，会返回第二个参数写的那个元素。

示例代码1：

str_list = []
for i in range(5):
    str_num = 'num' + str(i+1)
    str_list.append(str_num)

print(str_list)
# 只传第一个参数
it = iter(str_list)
for _ in range(8):
    res = next(it)
    print(res)

运行结果：

示例代码2：

str_list = []
for i in range(5):
    str_num = 'num' + str(i+1)
    str_list.append(str_num)

print(str_list)
# 传两个参数
it = iter(str_list)
for _ in range(8):
    # res = next(it, -1)
    res = next(it, '-1')
    print(res)

运行结果：