Python空白readlines [重复]

Question

用户数据库文件：

line1
line2
line3

代码：

with open("userdb","r",encoding='utf-8') as fl:
    user_count = len(fl.readlines())
    print(fl.readlines())
    print(user_count)

代码输出：

[]
3

长度没有问题，但无法打印线条。为什么以及如何解决这个问题？

Answer 1

readlines 单次打开文件后只能调用一次：

with open("userdb","r",encoding='utf-8') as fl:
    all_lines = fl.readlines()
    user_count = len(all_lines)
    print(all_lines)
    print(user_count)