题目

【加试题】小明编写了一个统计字符串中数字字符串之和的VB程序（如字符串“ab12.3cd34ef9”,中数字字符串之和为58：12+3+34+9），运行界面如图所示。在文本框Text1中输入字符串s，单击“统计”按钮Command1，在Label3中输出统计结果。 实现上述功能的VB程序代码如下，但加框处代码有错，请改正。 Private Sub Command1_Click()   Dim s As String, ch As String   Dim ch2 As String, sum As Double   Dim n As Integer, i As Integer   s = Text1.Text   n = Len(s)   i = 1: sum = 0   Do While                                    ＇①     ch = Mid(s, i, 1)     If ch >= "0" And ch <= "9" Then       j = i       ch2 = Mid(s, j, 1)       Do While ch2 >= "0" And ch2 <= "9"         j = j + 1         ch2 = Mid(s, j, 1)       Loop       sum = sum + Val（ ）     ＇②       i = j     End If     i = i + 1   Loop   Label3.Caption = Str(sum) End Sub ① ②  答案：【1】i<=n或i<n+1【2】Mid(s,i,j-1)

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