Cint 小数部分超过0.5的部分都进位，不分正负
例如：Cint（2.51）=3 Cint（-2.51）=-3
小于等于0.5的部分都舍去，不分正负
例如：Cint(2.49)=2 Cint(-2.49)=-2
Cint(2.5)=2 Cint(-2.5)=-2
Int 取到的是小于这个数的最大整数
例如:
Int(2.49)=2 Int(2.50)=2 Int(2.51)=2
Int(-2.49)=-3 Int(-2.50)=-3 Int(-2.51)=-3
Round 确定好保留的位数后，后面的直接四舍五入
例如：
Round(2.459,2)=2.46
Round(2.454,2)=2.45
Round(-2.459)=-2.46
Round(-2.454,2)=-2.45
Fix 省略小数位，即直接截走小数位
例如
Fix(2.51)=2 Fix(2.49)=2
Fix(-2.49)=-2 Fix(-2.51)=-2
在实际操作中验证：
Private Sub Command1_Click()
List1.AddItem "Cint(2.49)=" & CStr(CInt(2.49))
List1.AddItem "Cint(-2.49)=" & CStr(CInt(-2.49))
List1.AddItem "Cint(2.50)=" & CStr(CInt(2.5))
List1.AddItem "Cint(-2.50)=" & CStr(CInt(-2.5))
List1.AddItem "Cint(2.12)=" & CStr(CInt(2.12))
List1.AddItem "Cint(-2.12)=" & CStr(CInt(-2.12))
List1.AddItem "Cint(2.51)=" & CStr(CInt(2.51))
List1.AddItem "Cint(-2.51)=" & CStr(CInt(-2.51))
List1.AddItem " "
List1.AddItem "Int(2.49)=" & CStr(Int(2.49))
List1.AddItem "Int(-2.49)=" & CStr(Int(-2.49))
List1.AddItem "Int(2.50)=" & CStr(Int(2.5))
List1.AddItem "Int(-2.50)=" & CStr(Int(-2.5))
List1.AddItem "Int(2.12)=" & CStr(Int(2.12))
List1.AddItem "Int(-2.12)=" & CStr(Int(-2.12))
List1.AddItem "Int(2.51)=" & CStr(Int(2.51))
List1.AddItem "Int(-2.51)=" & CStr(Int(-2.51))
List1.AddItem "Int(-0.51)=" & CStr(Int(-0.51))
List1.AddItem "Int(0.51)=" & CStr(Int(0.51))
List1.AddItem " "
List1.AddItem "Round(2.459,2)=" & CStr(Round(2.459, 2))
List1.AddItem "Round(-2.459,2)=" & CStr(Round(-2.459, 2))
List1.AddItem "Round(2.454,2)=" & CStr(Round(2.454, 2))
List1.AddItem "Round(-2.454,2)=" & CStr(Round(-2.454, 2))
List1.AddItem " "
List1.AddItem "fix(2.45)=" & CStr(Fix(2.45))
List1.AddItem "fix(2.51)=" & CStr(Fix(2.51))
List1.AddItem "fix(-2.49)=" & CStr(Fix(-2.49))
List1.AddItem "fix(-2.51)=" & CStr(Fix(-2.51))
End Sub
