下面程序的功能是把文件file1.txt中重复字符去掉后(即若干多个字符相同，则只保留一个)写入文件file2.txt。请填空。
Private Sub Command1_Click()
Dim inchar As String, temp As String, outchar As String
outchar=""
Open"filel.txt" For Input As#1
Open"file2.txt" For Input As# (12)
n=LOF( (13) )
inchar=Input $ (n，1)
For k=1 To n
temp=Mid(inchar,k,1)
If InStr(outchar, temp)= (14) Then
outchar=outchar＆temp
End If
Next k
Print #2， (15)
Close#2
Close#1
End Sub