如何用VB编写替换.txt文件里的指定字符啊？

dim k as string,s as string
ffff = combo1.text
open "路径.txt" for input as #1 '读出
do while not eof(1)
line input #1 ,k
s = s & k & vbcrlf
loop
close #1

s = replace(s,"dddd",ffff)
open "路径.txt" for output as #1 '写入
print #1 , s
close #1

如果处理的文件不大的话，直接将整个文件读到一个String变量里边
然后用Replace函数处理下再写回去就行了
如果文件比较大就分段处理