VB6 overflow error with large integers

问题:

I am trying to set an integer value as such:

Dim intID as integer
intID = x * 10000

This works ok when x is 3 or less. But when x is 4, this gives me the error:

run-time error 6 Overflow

I don't understand why this is. I can set intID to 40000 directly without any problems, so it's obviously capable of storing large numbers.

回答1:

You *cannot set a vb6 integer to 40000 as they are signed 16 bit numbers so +32767 is the maximum.

Long is the 32 bit type.

However as a caveat, if you were to:

Dim lngID As Long
lngID = 4 * 10000

You would still get an overflow as literal numbers default to Integer, to correct that just type one as long with & or cast one as long using CLng():

Dim lngID As Long
lngID = 4 * 10000&
lngID = 4 * CLng(10000)

Update:

回答2:

in VB6, the Integer type is a whole number which ranges from -32768 to 32767.

You would be best using the Long type here.

回答3:

In VB Integer variable range is -32,768 to 32,767 If any variable value is more than this range in your program,you have to declare Data type Long instead of Integer.

Dim intID as integer
intID = x * 10000

Dim lngID AS Long

lngID = x * CLng(10000)
' if 10000
' whatever you want to be