3.1415926535
8979323846
2643383279
with open('pi_digits.txt') as f: # 默認(rèn)模式為‘r'，只讀模式
  contents = f.read() # 讀取文件全部?jī)?nèi)容
  print contents # 輸出時(shí)在最后會(huì)多出一行（read()函數(shù)到達(dá)文件末會(huì)返回一個(gè)空字符，顯示出空字符就是一個(gè)空行）
  print '------------'
  print contents.rstrip() # rstrip()函數(shù)用于刪除字符串末的空白
3.1415926535
8979323846
2643383279

------------
3.1415926535
8979323846
2643383279

with open('pi_digits.txt') as f:  
for line1 in f:    
print line1 # 每行末尾會(huì)有一個(gè)換行符
print '------------'
for line2 in f:    
print line2.rstrip() # 此時(shí)文件已經(jīng)讀完，line2指向文本末尾，因此不會(huì)有輸出
3.1415926535

8979323846

2643383279

----------

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(kāi)文本進(jìn)行讀取
for line2 in f:    
print line2.rstrip() # 刪除字符串末尾的空白
3.1415926535

8979323846

2643383279

------------
3.1415926535
8979323846
2643383279

with open('pi_digits.txt') as f: 
lines = f.readlines() # 讀取文本中所有內(nèi)容，并保存在一個(gè)列表中，列表中每一個(gè)元素對(duì)應(yīng)一行數(shù)據(jù)
print lines # 每一行數(shù)據(jù)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
['3.1415926535\n', '8979323846\n', '2643383279\n']
------------
3.1415926535
8979323846
2643383279
------------
3.141592653589793238462643383279

filename = 'write_data.txt'
with open(filename,'w') as f: # 如果filename不存在會(huì)自動(dòng)創(chuàng)建， 'w'表示寫數(shù)據(jù)，寫之前會(huì)清空文件中的原有數(shù)據(jù)！
f.write("I am Meringue.\n")
f.write("I am now studying in NJTECH.\n")

I am Meringue.
I am now studying in NJTECH.

with open(filename,'a') as f: # 'a'表示append,即在原來(lái)文件內(nèi)容后繼續(xù)寫數(shù)據(jù)（不清楚原有數(shù)據(jù)）
f.write("I major in Machine learning and Computer vision.\n")

I am Meringue.
I am now studying in NJTECH.
I major in Machine learning and Computer vision.