求前n项的和【VB代码实现】

求的和。

For语句实现

Private Sub Command1_Click()
    Dim s As Long       '变量s表示存储前i项的和
    Dim n As Integer
    Dim i As Integer    '变量i表示第i项
    n = Val(Text1.Text)
    s = 0               '变量s初始化为0
    For i = 1 To n      'For循环的含义：计算求出前i项的和
        s = s + i       '通项公式
    Next i
    Label4.Caption = Str(s)
End Sub

Do While语句实现

Private Sub Command1_Click()
    Dim s As Long, i As Integer, n As Integer
    n = Val(Text1.Text)
    s = 0
    i = 1
    Do While i <= n
        s = s + i
        i = i + 1
    Loop
    Label4.Caption = Str(s)
End Sub

学习要求：

1、读懂题意，根据每一项的变化写出通项公式。

2、设定相应的变量来解决问题，理解各变量的作用。