def str1(list1):     c="".join(map(str,list1))     return c     a=[1, 2, 3, 4, 5, 6, 7, 8, 9] print(str1(a)) #方法二 def str2(list2):     d=0     for i in list2:         d=d*10+i     return d a=[1, 2, 3, 4, 5, 6, 7, 8, 9] print(str2(a)) #方法三：高阶函数 from functools import reduce def Change_list(list):     def fn(x,y):         return x*10+y         return reduce(fn,list) a=[1, 2, 3, 4, 5, 6, 7, 8, 9] print(Change_list(a))