Question

一段VB代码输入VB6.0中，却无法运行，不知道哪里错了

Public Function fun(s1 As String)
Dim s1 As String
For i = 1 To Len(s)
s1 = s1 + UCase(Mid(s, i, 1))
Next i
fun = s1

End Function

Private Sub Command1_Click()
Dim strl As String, str2 As String
str1 = InputBox("请输入一个字符串")
Print
Print " 输入的字符串为;"; str1
str2 = fun(str1)
Print
Print "转换后的字符串为;"; str2

End Sub
代码的作用是将输入的字符串，变为大写

Answer 1

程序十分复杂，应该写：

Private Sub Command1_Click()
Dim strl As String, str2 As String
str1 = InputBox("请输入一个字符串")
Print
Print " 输入的字符串为;"; str1
str2 = UCase(str1)
Print
Print "转换后的字符串为;"; str2
End Sub

如果你执意要自己写，那么：
Public Function fun(s1 As String)
Dim res As String
For i = 1 To Len(s)
res = res & UCase(Mid(s1, i, 1)) '注意s改为s1，字符串连接用&
Next i
fun = res
End Function

Private Sub Command1_Click()
Dim strl As String, str2 As String
str1 = InputBox("请输入一个字符串")
Print
Print " 输入的字符串为;"; str1
str2 = fun(str1)
Print
Print "转换后的字符串为;"; str2
End Sub

Answer 2

Public Function fun(s1 As String)
Dim a As String
For i = 1 To Len(s1)
a = a + UCase(Mid(s1, i, 1))
Next i
fun = a
End Function

Private Sub Command1_Click()
Dim str1 As String, str2 As String
str1 = InputBox("请输入一个字符串")
Print
Print " 输入的字符串为;"; str1
str2 = fun(str1)
Print
Print "转换后的字符串为;"; str2

End Sub

错误太多了，我不一一说了，只给你个修改后的正确语句吧

Answer 3

你的fun函数是没有问题的,就是Print函数有问题,
其实你要测试可以用msgbox("文本的"),这个函数很简单的

Answer 4

的确错误好多