python中eval的使用

eval函数就是实现str与list、dict、tuple之间的转化
栗子：

a = "[[1,2], [3,4], [5,6], [7,8], [9,0]]"
aa = eval(a)
print(type(a))
print(type(aa))
b = "{1: 'a', 2: 'b'}"
bb = eval(b)
print(type(b))
print(type(bb))
c = "([1,2], [3,4], [5,6], [7,8], (9,0))"
cc = eval(c)
print(type(c))
print(type(cc))
d = "3+5"
dd = eval(d)
print(dd)

输出结果：
<class 'str'>
<class 'list'>
<class 'str'>
<class 'dict'>
<class 'str'>
<class 'tuple'>
8