在C ++中添加两个double变量

Question

我读到double的精度为15位数字。但是，我不知道为什么会这样。

folder_name = "out%s.txt"
folder_number = 0


folder_name = folder_name % folder_number
f = open(folder_name, 'w+')

for domain in millions_of_domains:
   try:
      response_json = send_whois_query(domain)
      f.write(response_json)
   except FileGreaterThan100MbException:
      folder_number += 1
      folder_name = folder_name % folder_number
      f = open(folder_name, 'w+')
      f.write(response_json)

输出为-

17.0001

17