python把str转换为int

 def str2int(s):
     def fn(x,y):
         return x+y
     def char2num(s):
         return {'':0,'':1,'':2,'':3,'':4,'':5,'':6,'':7,'':8,'':9}[s]
     return reduce(fn,map(char2num,s))

 print(str2int(''))