在python中递归地将一个列表复制到另一个列表

return string_copy(k,s.append(k[i]),i+1)

名单 append() 方法不返回更新的列表;它将新项添加到位并返回 None .

所以下一个电话 string_copy() s .

最终解决方案是:

def string_copy(k,s,i):
  if (i == len(k)):
    return s
  else:
    s.append(k[i])
    return string_copy(k,s,i+1)

def main():
   print("enter the string you want to copy:")
   k = input()
   s = ""
   i = 0;
   print("the type of k is:", type(k))
   res = string_copy(list(k),list(s),i)
   print("the desired results are:","\n", "".join(res))
if __name__ == "__main__": main()        

def string_copy(k):
  if (len(k) == 0):
    return k
  else:
    return k[0] + string_copy(k[1:])

def main():
  print("enter the string you want to copy:")
  k = input()
  print("the type of k is:", type(k))
  res = string_copy(k)
  print("the copied string is:","\n",res)
if __name__ == "__main__": main()