作用一:

①将字符串转化成列表

a = "[[1,2],[3,4]]"
b = eval(a)
print(b)
>>>[[1:2],[3:4]]

②将字符串转化成字典

a = "{'name':'wangfuyan','age':'21'}"
print(a)
print(type(a))
b =eval(a)
print(type(b))
>>>{'name':'wangfuyan','age':'21'}

③将字符串转化成元祖

a = "([1,2],[3,4],[5,6])"
print(a)
print(type(a))
b = eval(a)
print(b)
print(type(b))
>>>([1,2],[3,4],[5,6])