Android Question Solved - String to long integer odd issue

[padvou]

Hi!
Consider this string: 637406139915958403 and this: 637406139915958402
using this sub:

Sub CI(str As String) As Long
    If IsNumber(str) Then
    Try
        Dim ret As Long
        ret = str
        Return ret
    Catch
        Return 0
    End Try
    Else
        Return 0
    End If
End Sub

returns 637406139915958400 in both strings.
Why??

 

[OliverA]

Almost looks like the values are first converted to a Double and then to an Int a Long

    Dim one As String = "637406139915958402"
    Dim two As String = "637406139915958403"
    Dim double1 As Double = one
    Dim double2 As Double = two
    Log($"$18{double1}"$)
    Log($"$18{double2}"$)

Output:

double1: 637,406,139,915,958,400
double2: 637,406,139,915,958,400

 

[OliverA]

Confirmed

    Dim one As String = "637406139915958402"
    Dim long1 As Long = one

The resulting Java code fo the long1 assignment is

_long1 = (long)(Double.parseDouble(_one));

 

[OliverA]

A solution: Use @agraham's BigNumbers library (https://www.b4x.com/android/forum/threads/bignumbers-library.9540/#content):

    Dim one As String = "637406139915958402"
    Dim bigN As BigInteger
    bigN.Initialize(one)
    Dim long1 As Long = bigN.LongValue
    Log($"long1: ${long1}"$)

Result:

long1: 637406139915958402