程序代码：

clear all

public ga_Keys[30]
ga_Keys[1]  = CREATEOBJECT("Key_t", "MC", "MC")
ga_Keys[7]  = CREATEOBJECT("Key_t", "MR", "MR")
ga_Keys[13]  = CREATEOBJECT("Key_t", "MS", "MS")
ga_Keys[19]  = CREATEOBJECT("Key_t", "M1", "M+")
ga_Keys[25]  = CREATEOBJECT("Key_t", "M2", "M-")
ga_Keys[2] = CREATEOBJECT("Key_t", "(", "(")
ga_Keys[3] = CREATEOBJECT("Key_t", ")", ")")
ga_Keys[4]  = CREATEOBJECT("Key_t", "BS", "←")
ga_Keys[5]  = CREATEOBJECT("Key_t", "C1", "CE")
ga_Keys[6]  = CREATEOBJECT("Key_t", "C2", "C")
ga_Keys[8] = CREATEOBJECT("Key_t", "7", "7")
ga_Keys[9] = CREATEOBJECT("Key_t", "8", "8")
ga_Keys[10] = CREATEOBJECT("Key_t", "9", "9")
ga_Keys[11] = CREATEOBJECT("Key_t", "/", "/")
ga_Keys[12] = CREATEOBJECT("Key_t", "sqrt", "√")
ga_Keys[14] = CREATEOBJECT("Key_t", "4", "4")
ga_Keys[15] = CREATEOBJECT("Key_t", "5", "5")
ga_Keys[16] = CREATEOBJECT("Key_t", "6", "6")
ga_Keys[17] = CREATEOBJECT("Key_t", "*", "*")
ga_Keys[18] = CREATEOBJECT("Key_t", "%", "%")
ga_Keys[20] = CREATEOBJECT("Key_t", "1", "1")
ga_Keys[21] = CREATEOBJECT("Key_t", "2", "2")
ga_Keys[22] = CREATEOBJECT("Key_t", "3", "3")
ga_Keys[23] = CREATEOBJECT("Key_t", "-", "-")
ga_Keys[24] = CREATEOBJECT("Key_t", "inverse", "1/x")
ga_Keys[26] = CREATEOBJECT("Key_t", "0", "0")
ga_Keys[27]  = CREATEOBJECT("Key_t", "sign", "+/-")
ga_Keys[28] = CREATEOBJECT("Key_t", ".", ".")
ga_Keys[29] = CREATEOBJECT("Key_t", "+", "+")
ga_Keys[30] = CREATEOBJECT("Key_t", "=", "=")

public gc_Expression, gc_Result
gc_Expression = ""
gc_Result = ""

set decimals to 4
on error do errHandler with Error(), Message(), Message(1), Program(), Lineno()
Main()
on error

clear all
return

procedure errHandler(merror, mess, mess1, mprog, mlineno)
          MessageBox(Str(mlineno) + "表达式错误：" + mess)
endproc


procedure Main()
       local lo_MainForm
       lo_MainForm = NewObject("C_Form")
       lo_MainForm.show
       read events
endproc    

define class Key_t as Custom
       ID = ""
       Caption = ""
      
       procedure Init(tc_ID, tc_Caption)
            with This
                 .ID = tc_ID
                 .Caption = tc_Caption
            endwith
       endproc
enddefine

Define Class C_Button as CommandButton
       Width = 50
       Height = 50
       *FontName = "Terminal"
       Themes = 0
       FontSize = 20
      
       *- 键名属性
        Key = ""
       
        Procedure Init(t_Key)
              With This
                   .Key = t_Key
                   .Caption = .Key.Caption
              EndWith
        EndProc
EndDefine

define class C_Form as Form
       MaxButton = .F.
       Caption = "    计算器"
       Icon = 'D:\VFP\ico\rr.ico'
       AutoCenter = .T.
      
       add object C_display as Container with Width = 350, Height = 50,;
                                 BorderWidth = 2
       add object C_btnGroup as Container with Width = ThisForm.C_display.Width, Height = 300,;
                                 BorderWidth = 0
            
       procedure C_display.Init
          with This
            .SpecialEffect = 1
            .AddObject("mem_dpy", "Container")  && mem_dpy 的意思是memory_display
            .mem_dpy.Top = 5
            .mem_dpy.Left = 5
            .mem_dpy.Width = 40
            .mem_dpy.Height = 40
            .mem_dpy.SpecialEffect = 1
           
            .AddObject("epn_dpy", "Label")    && epn_dpy 的意思是expression_display
            .epn_dpy.Top = .mem_dpy.Top
            .epn_dpy.Left = .mem_dpy.Left * 2 + .mem_dpy.Width
            .epn_dpy.Width = .Width - .mem_dpy.Width - .mem_dpy.Left * 2
            .epn_dpy.Height = .Height/2 - .mem_dpy.Top
            *.epn_dpy.BackColor = Rgb(0, 0, 255)
        
            .AddObject("rst_dpy", "Label")   && rst_dpy 的意思是result_display
            .rst_dpy.Top = .Height/2
            .rst_dpy.Left = .epn_dpy.Left
            .rst_dpy.Width =  .epn_dpy.Width
            .rst_dpy.Height = .epn_dpy.Height
            *.rst_dpy.BackColor = Rgb(255, 0, 0)
           
            .SetAll("Visible", .T.)
            .SetAll("Caption", "0.")
            .SetAll("Alignment", 1)
            .SetAll("BorderWidth", 2)
            .SetAll("FontSize", 14)
          endwith
       endproc
      
       Procedure C_btnGroup.Init
             Local lc_KeyName
             Local ln_Space
             Local ln_Index, ln_Top, ln_Left
             ln_Top = 0
             ln_Left = 0
             ln_Space = 10
             For ln_Index = 1 to Alen(ga_Keys, 0)
                  lc_KeyName = "Key_" + Padl(ln_Index, 2, '0')
                 This.AddObject(lc_KeyName, "C_Button", ga_Keys[ln_Index])
                 With This.&lc_KeyName
                      If  InList(ln_Index, 7, 13, 19, 25)
                          ln_Top = ln_Top + .Height + ln_Space
                          ln_Left = 0
                      EndIf
                      If InList(ln_Index, 8, 9, 10, 14, 15, 16, 20, 21, 22,;
                                26, 27, 28, 12, 18, 24)
                             .ForeColor = Rgb(0, 0, 255)
                      Else
                             .ForeColor = Rgb(255, 0, 0)      
                      EndIf
                      .Top = ln_Top
                      .Left = ln_Left
                      .Visible = .T.
                      .Themes = 0 
                      ln_Left = ln_Left + .Width + ln_Space                                      
                 EndWith
             Next
       EndProc
      
       procedure Init
            with This
            .C_display.Top = 35
            .C_display.Left = 10
            .C_btnGroup.Top = .C_display.Top + .C_display.Height + 10
            .C_btnGroup.Left = .C_display.Left
            .Width = .C_display.Width + 20
            .Height = .C_btnGroup.Top + .C_btnGroup.Height
            endwith
       endproc                    

procedure destroy
     clear events
endproc

enddefine