python计算算术表达式的怪异行为(5-1//2)
python's weird behaivor of evaluating the arithmetic expression(5-1//2)
print(5-1//2)
这个表达式给出结果 5
如何？
我的尝试：
x=5-1//2
x=5-1 #(-1//2 gives -1)
x=4
但是 python 说的是 5
怎么样？
The - in 5-1//2 is a binary -. What you have checked with -1//2 is a unary -. These have different precedence. The way you separated 5-1//2 into 5+(-1//2) is not how it is actually evaluated.
-- comment by MisterMiyagi，已更正数学并添加 link
print(5-1//2)
这个表达式给出结果 5
如何？
我的尝试：
x=5-1//2
x=5-1 #(-1//2 gives -1)
x=4
但是 python 说的是 5
怎么样？
The
-in5-1//2is a binary-. What you have checked with-1//2is a unary-. These have different precedence. The way you separated5-1//2into5+(-1//2)is not how it is actually evaluated.
-- comment by MisterMiyagi，已更正数学并添加 link