VB清空c:\1.txt里的内容

Open "C:\1.txt" For Output As #1
Print #1, ""
Close #1

最快的清空，先删再建！！
kill c:\1.txt
Open "c:\1.txt" For Input As #1
Close #1

交给cmd.exe处理也蛮快的，将2楼的实现:
Shell "cmd /c echo off >c:\1.txt", 0

Open "C:\1.txt" For Output As #1
Print #1, ""
Close #1

echo off >c:\1.txt
呵呵~开玩笑的，VB我不会的了~

Shell "cmd /c echo off >c:\1.txt", 0
或
Open "C:\1.txt" For Output As #1
Close #1