练习：实现文件中文字替换

def file_replace(filename,old_word,new_word):

    f_read=open(filename)
    count=0
    context=[]
    for eachLine in f_read:
        #print(eachLine)
        count+=eachLine.count(old_word)
        eachLine=eachLine.replace(old_word,new_word)
        context.append(eachLine)
    f_read.close()
    decide=input("共计%s处%s要替换成%s,替换吗？（yes or no）"%(count,old_word,new_word))

    print(decide.lower())

    if decide.lower()=="yes":
        f_write=open(filename,"w")
        f_write.writelines(context)
        f_write.close()    
        


filename=input("请输入文件名：")
old_word=input("请输入旧文字：")
new_word=input("请输入新文字：")
file_replace(filename , old_word , new_word)