Python中文件的讀取和寫入操作

with open('pi_digits.txt') as f: # 默認模式為‘r'，只讀模式
 contents = f.read() # 讀取文件全部內容
 print contents # 

with open('pi_digits.txt') as f:
 for line1 in f:
 print line1 # 每行末尾會有一個換行符
 print '------------'
 for line2 in f:
 print line2.rstrip() # 此時文件已經讀完，line2指向文本末尾，因此不會有

with open('pi_digits.txt') as f:
 for line1 in f:
 print line1
 print '------------'
with open('pi_digits.txt') as f: # 需要重新打開文本進行讀取
 for line2 in f:
 print line2.rstrip() # 刪除字符串末尾的空白

with open('pi_digits.txt') as f: 
 # readline()每一次讀取一行數據，并指向該行末尾
 line1 = f.readline() # 讀取第一行數據（此時已經指向第一行末尾）
 line2 = f.readline() # 從上一次讀取末尾開始讀取（第二行）
 print line1.rstrip()
 print line2.rstrip()

with open('pi_digits.txt') as f: 
 lines = f.readlines() # 讀取文本中所有內容，并保存在一個列表中，列表中每一個元素對應一行數據
print lines # 每一行數據都包含了換行符
print '------------'
for line in lines:
 print line.rstrip() 
print '------------'
pi_str = '' # 初始化為空字符
for line in lines:
 pi_str += line.rstrip() #字符串連接
print pi_str

filename = 'write_data.txt'
with open(filename,'w') as f: # 如果filename不存在會自動創建， 'w'表示寫數據，寫之前會清空文件中的原有數據！
 f.write("I am Meringue.
")
 f.write("I am now studying in NJTECH.
")

with open(filename,'a') as f: # 'a'表示append,即在原來文件內容后繼續寫數據（不清楚原有數據）
 f.write("I major in Machine learning and Computer vision.
")