各位帮帮忙，急急急。。。n5=cdbl(n1*n2+n3+n4) and 65535,当n1*n2+n3+n4太大时报溢出？

[yyb2000]

[liyang]

你的 n1,n2,n3,n4是何类型。可以n1#*n2#+n3#+n4#,把每一个转化为double

[liyang]

是这样:cdbl(n1)*cdbl(n2)+cdbl(n3)+cdbl(n4)，即把每个变量均转化为不超限制的类型。

[yyb2000]

我早试过,不行,
n5=cdbl(n1)*cdbl(n2)+cdbl(n3)+cdbl(n4) 时不会报错,一但
n5=(cdbl(n1)*cdbl(n2)+cdbl(n3)+cdbl(n4)) and 65535,wrong?

[liyang]

只好自己写一个
Private Function MyAnd(ByVal varSour As Variant, ByVal varMod As Variant) As Long

Dim I As Long
Dim bytTemp() As Byte
Dim dblRem As Double, dblRem2 As Double
Dim lResult As Long
Dim lReturn As Long
Dim n3 As Double
Dim lModLen As Long

ReDim bytTemp(0)
dblRem = varSour
Do Until dblRem < 2
dblRem2 = Int(dblRem / 2)
bytTemp(UBound(bytTemp)) = dblRem - dblRem2 * 2
ReDim Preserve bytTemp(UBound(bytTemp) + 1)
dblRem = dblRem2
Loop
bytTemp(UBound(bytTemp)) = dblRem

Dim bytMod() As Byte
Dim dblTemp1 As Double, dblTemp As Double
ReDim bytMod(0)
dblTemp = varMod
Do Until dblTemp < 2
dblTemp1 = Int(dblTemp / 2)
bytMod(UBound(bytMod)) = dblTemp - dblTemp1 * 2
ReDim Preserve bytMod(UBound(bytMod) + 1)
dblTemp = dblTemp1
Loop
bytMod(UBound(bytMod)) = dblTemp
lModLen = UBound(bytMod)

For I = 0 To IIf(UBound(bytTemp) > lModLen, lModLen, UBound(bytTemp))
lResult = lResult Or bytTemp(I) * 2 ^ I
Next I
MyAnd = lResult And varMod

End Function

[yyb2000]

liyang:
如下不能通过
dim a,b as double
a=65535# * 65535#
b=myand(a,65535)

[Un1]

使用and时，vb会自动做clng和cbool转换，如果double值大于&h7fffffff或小于&h80000000当然要出错。