Python 讀取文件的幾種方法

0. 讀取文件

# 1
f = open('fileName', 'r')
# do something with f
f.close()

# 2
with open('fileName', 'r') as f:
    # do something with f
    # no need to close, and will close automatically if exception rised

1. 全部一口氣讀取，一個文件是一個list，每一個元素（str）是一行

lines = f.readlines()
for line in lines:
    fun(line)

2. 逐行讀取

簡易版：每次循環只能讀取一行

for line in f:
    fun(f)

自由一點：每次可以視情況，讀取多行(推薦，多寫一行，獲得更多的控制權)

line = f.readline()
while line:
    fun(line, f) # can read more line by f.readline()
    line = f.readline()