python练习六十二：文件处理，往文件中所有添加指定的前缀

往文件中所有添加指定的前缀

方法一：open方法

f_r = open('text.txt')
f_w = open('text_new.txt','w+')
i = 0
while True:
    i += 1
    line = f_r.readline()
    if not line:
        break
    f_w.write('%02d'%i + '.python'+ ' ' +line)
f_r.close()
f_w.close()
f_wr = open('text_new.txt','r')
lines = f_wr.readlines()
for i in lines:
    print(i)
f_wr.close()

方法二：with open方法

with open('text.txt') as f_r:
     line = f_r.readline()
     with open('text_new.txt','w') as f_w:
         i = 0
         while True:
             i += 1
             line = f_r.readline()
             if not line:
                 break
#             f_w.write('%02d'%i + '.python'+ ' 'len+line)  #格式化输出方法一
             f_w.write('{:>2}{}{}{}'.format(i,'.python',' ',line)) #格式化输出方法二

with open('text_new.txt','r') as f_wr:
     lines = f_wr.readlines()
     for i in lines:
         print(i)

执行结果：

01.python jave
02.python go
03.python shell
04.python perl