python中打印元组和列表的区别

Question

当我在列表和元组之间更改输出类型时，一个显示输出，而另一个仅显示结果的位置。为什么会这样？

>>> symbol = '123456789'
>>> (s for s in symbol)
<generator object <genexpr> at 0x7fc0e9e2fbf8>
>>> [s for s in symbol]
['1', '2', '3', '4', '5', '6', '7', '8', '9']

Answer 1

(s for s in symbol) 是生成器理解。类似于：

symbol = '123456789'
def func():
    for s in symbol:
        yield s

g = func()
print(g)
<generator object func at 0x7ffff7e59410>

print(tuple(g)) 
('1', '2', '3', '4', '5', '6', '7', '8', '9')

如果您将生成器提供给list() 或tuple()，则生成器将运行。