尝试使用InStr函数，该函数返回找到字符的字符串中的索引.如果InStr返回0，则找不到该字符串.

Try using the InStr function which returns the index in the string at which the character was found. If InStr returns 0, the string was not found.

If InStr(myString, "A") > 0 Then

InStr MSDN网站

对于分配给newStr的行上的错误，也将oldStr.IndexOf转换为该InStr函数.

For the error on the line assigning to newStr, convert oldStr.IndexOf to that InStr function also.

Left(oldStr, InStr(oldStr, "A"))