文件按行读取小技巧

文件按行读取，大多数可能如下：

file = open("a.txt") 
while 1:
    line = file.readline()
    if not line:
        break
file.close()

但使用文件迭代更加简约

file = open("sample.txt") 
for line in file:
    pass 
file.close()