import sys  f=open('test.txt','a+') a='123' b='456' print >> f,a,b f.close() 

import sys  f=open('a.txt','w') old=sys.stdout #將當前系統輸出儲存到臨時變量 sys.stdout=f #輸出重定向到文件 print 'Hello World!' #測試一個打印輸出 sys.stdout=old  #還原系統輸出 f.close() print open('a.txt','r') # 錯誤的方法，僅用于查看輸出，了解python print open('a.txt','r').read() 

import sys year=1 years=15 bj=10000 rate=0.05 f=open('total.txt','w+') while year < years:    bj=bj*(1+rate)    print >> f,"第%d年，本息合計%0.2f" % (year,bj)    year+=1 

class FakeOut:  def __init__(self):   self.str=''   self.n=0  def write(self,s):   self.str+="Out:[%s] %s/n"%(self.n,s)   self.n+=1  def show(self): #顯示函數，非必須   print self.str  def clear(self): #清空函數，非必須   self.str=''   self.n=0 f=FakeOut() import sys old=sys.stdout sys.stdout=f print 'Hello weird.' print 'Hello weird too.' sys.stdout=old f.show() # 輸出： # Out:[0] Hello weird. # Out:[1]  # Out:[2] Hello weird too. # Out:[3]