如何在python中计算输入行数

filename = input("请输入文件名：")
with open(filename, 'r') as file:
    lines = file.readlines()
    line_count = len(lines)
    print("行数：", line_count)

filename = input("请输入文件名：")
line_count = 0
with open(filename, 'r') as file:
    for line in file:
        line_count += 1
print("行数：", line_count)

filename = input("请输入文件名：")
with open(filename, 'r') as file:
    content = file.read()
    line_count = len(content.splitlines())
print("行数：", line_count)