form1.frm

vb 的例子

VERSION 5.00
Begin VB.Form Form1 
   Caption         =   "解一元二次方程"
   ClientHeight    =   3525
   ClientLeft      =   60
   ClientTop       =   345
   ClientWidth     =   6495
   LinkTopic       =   "Form1"
   ScaleHeight     =   3525
   ScaleWidth      =   6495
   StartUpPosition =   3  'Windows Default
   Begin VB.CommandButton Command1 
      Caption         =   "计算"
      Height          =   495
      Left            =   4560
      TabIndex        =   5
      Top             =   2520
      Width           =   1695
   End
   Begin VB.TextBox Text5 
      Height          =   495
      Left            =   3360
      TabIndex        =   4
      Text            =   "Text5"
      Top             =   1080
      Width           =   1455
   End
   Begin VB.TextBox Text4 
      Height          =   495
      Left            =   3360
      TabIndex        =   3
      Text            =   "Text4"
      Top             =   360
      Width           =   1455
   End
   Begin VB.TextBox Text3 
      Height          =   495
      Left            =   720
      TabIndex        =   2
      Text            =   "Text3"
      Top             =   1800
      Width           =   1575
   End
   Begin VB.TextBox Text2 
      Height          =   495
      Left            =   720
      TabIndex        =   1
      Text            =   "Text2"
      Top             =   1080
      Width           =   1575
   End
   Begin VB.TextBox Text1 
      Height          =   495
      Left            =   720
      TabIndex        =   0
      Text            =   "Text1"
      Top             =   360
      Width           =   1575
   End
   Begin VB.Label Label5 
      Caption         =   "x2:"
      Height          =   255
      Left            =   2880
      TabIndex        =   10
      Top             =   1200
      Width           =   255
   End
   Begin VB.Label Label4 
      Caption         =   "x1:"
      Height          =   255
      Left            =   2880
      TabIndex        =   9
      Top             =   480
      Width           =   255
   End
   Begin VB.Label Label3 
      Caption         =   "c:"
      Height          =   255
      Left            =   120
      TabIndex        =   8
      Top             =   1920
      Width           =   255
   End
   Begin VB.Label Label2 
      Caption         =   "b:"
      Height          =   255
      Left            =   120
      TabIndex        =   7
      Top             =   1200
      Width           =   255
   End
   Begin VB.Label Label1 
      Caption         =   "a:"
      Height          =   255
      Left            =   120
      TabIndex        =   6
      Top             =   480
      Width           =   255
   End
End
Attribute VB_Name = "Form1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Option Explicit

    Private Sub Command1_Click()
        Dim a As Single, b As Single, c As Single
        Dim sng1 As Single, sng2 As Single
        
        a = CSng(Text1.Text)
        b = CSng(Text2.Text)
        c = CSng(Text3.Text)
        If a = 0 Then
            If b = 0 Then
                Text4.Text = "方程无解。"
                Text5.Text = "方程无解。"
            Else
                Text4.Text = -c / b
                Text5.Text = "方程只有一个实根。"
            End If
        Else
            sng1 = b * b - 4 * a * c
            sng2 = Sqr(Abs(sng1)) / Abs(2 * a)
            If sng1 < 0 Then
                Text4.Text = CStr(-b / (2 * a)) & "+" & CStr(sng2) & "i"
                Text5.Text = CStr(-b / (2 * a)) & "-" & CStr(sng2) & "i"
            Else
                Text4.Text = -b / (2 * a) + Abs(sng2)
                Text5.Text = -b / (2 * a) - Abs(sng2)
            End If
        End If
    End Sub