为什么元组列表可以转换为字典，而元组的元组不能

Question

please try to execute this you should understand my question

a=[(x,1)]
b=((x,1))
c=((x,1),)
dict(a) #runs successfully 
dict(b) # gives error 
dict(c) #runs successfully

I want to understand why a and c are valid but b is not??

Answer 1

Variables "a" and "c" have the same structure, with an iterable holding a key-value pair {x: 1}, whereas variable "b" has the assignment statement of just ((x,1)), so python executes that as an equivalent to (x,1) because an tuple assignment statement with only one element needs to have the ending comma to signify that it is a "tuple", otherwise it is just parenthesis. Python doesn't really understand this structure as a "key-value" pair.