简单四则运算vb课程设计报告书

1、VB 课程设计书051 班学号 051299土木学院交通一设计题目：设计一个简单的四则运算程序表达式二设计思路： 1.将续的运算表达式看作是由若干个子表达式组成的。一个子表达式则由一个运算符和其两侧的运算数组成。若将这些子表达式用运算结果代替，则能起到简化运算结果的目的。利用数组，先将运算符找出来送入数组，再将其左右的两个数进行运算，再得出结果。三简易图示：IF存在“+”“-”“*”“/”THEN令=A(i)“+”“-”“*”“/”计算Val(a(I+1)+Val(a(I-1)orVal(a(I+1)-Val(a(I-1)orVal(a(I+1)*Val(a(I-1)orVal(a(I+1)/

2、Val(a(I-1)四程序：Dim val_Str() As StringDim zifu() As StringDim result As DoubleDim zhengfu() Aseger用于判断数据的正负Function jieguo(str As String) As Double不包含字符串的表达式的计算Dim s_AsegerReDim zifu(Len(str) + 2) ReDim zhengfu(Len(str) + 1) aa = Mid(str, i + 1, 1)If aa = - Or aa = + Or aa = * Or aa = / Then str = 0

3、& strs_= 0zifu(0) = For i = 0 To Len(str) zhengfu(i) = 1Next i = 0Do While i = 48 And bb 1 ThenFor i = 0 To s_Step 2If zifu(i + 1) = * Or zifu(i + 1) = / Then If zifu(i + 1) = * Thenzifu(i) = Val(zifu(i) * Val(zifu(i + 2)Elsezifu(i) = Val(zifu(i) / Val(zifu(i + 2) End IfFor j = i + 1 To s_ zifu(j) =

4、 zifu(j + 2)Nextzifu(s_- 1) = : zifu(s_) = s_= s_- 2i = i - 2 End IfNextresult = zifu(0) For i = 1 To s_Step 2If zifu(i) = - Then zifu(i + 1) = Val(zifu(i + 1) * (-1) result = result + zifu(i + 1)Nextjieguo = result Elsejieguo = zifu(0)End IfFor i = 0 To s_如果是除数为 0,则报错If zifu(i) = / And zifu(i + 1) = 0 Then MsgBox (no)End If Next iEnd FunctionPrivate Subd1_click()result = a(Text1.text)Label1.Caption = 计算结果 = + Format(result)End Sub五在技术允许的情况下，可改进方案：a)b)c)d)将基本函数加入表达式将括号加入表达式能够判断表达式能够判断除数 0六心得体会：通过这次课程设计，从宏观上讲，提高了自己的动手能力及主动学习的能力；