How to convert String (or Double) to SerialNumber

[newbieforever]

Hi!

If tst0 is a timestamp of a file, e.g. 20190217142630, defined as String (or as Double), how to convert it to tst as SerialNumber?

[fxm]

There are several possible methods.
See at Date Serials.

[newbieforever]

Thank you, fxm!

Code: Select all

Function Str2SerNum(ss As String) As Double
  Dim As Integer ye = Val(Mid(ss, 1, 4))
  Dim As Integer mo = Val(Mid(ss, 5, 2))
  Dim As Integer da = Val(Mid(ss, 7, 2))
  Dim As Integer ho = Val(Mid(ss, 9, 2))
  Dim As Integer mi = Val(Mid(ss, 11, 2))
  Dim As Integer se = Val(Mid(ss, 13, 2))
  Dim As Double  tst = DATESERIAL(ye, mo, da) + TIMESERIAL(ho, mi, se)
  Return tst
End Function

[counting_pine]

If you're happy to use the C runtime, you could use sscanf:

Code: Select all

#include "crt.bi"
#include "vbcompat.bi"

Function Str2SerNum(ss As String) As Double
  dim as long ye, mo, da, ho, mi, se
  sscanf(ss, "%4d%2d%2d%2d%2d%2d", @ye,@mo,@da,@ho,@mi,@se)
  Dim As Double  tst = DATESERIAL(ye, mo, da) + TIMESERIAL(ho, mi, se)
  Return tst
End Function

print now()
print Str2SerNum(format(now, "yyyymmddhhmmss"))

Otherwise, I'd recommend CInt(Mid(...)) instead of Val(Mid(...)), to avoid the floating-point math.

[Munair]

Otherwise, I'd recommend CInt(Mid(...)) instead of Val(Mid(...)), to avoid the floating-point math.

Why not use ValInt or in this case ValUInt directly?

[dodicat]

cint uses valint/vallng for strings anyway.
-- and it is easier to type in.

Code: Select all

#undef valint
#undef vallng

#ifdef valint
#undef valint
#endif

#ifdef vallng
#undef vallng
#endif

  'print valint("12.34")  'gone
  'print vallng("12.34") 'gone
 print cint("12.34")    'also gone
 sleep  

[fxm]

The keyword-name ValInt / ValLng can be misleading because the conversion is done to Long / LongInt (and not to Int / Long), whereas the name is consistent for CInt / CLng (and the others Cx).

[counting_pine]

Yeah, I used to recommend Valint(), but the legacy naming issues give some uncertainty about the size of the type returned. So Cint/Clng/Clngint/... is clearer, if you're happy with the idea of using them for conversions from string. That's something QB didn't support. (But then it didn't support Valint/... either.)

[dodicat]

Here is a summary

Code: Select all

 #undef valint
#undef vallng
#undef valuint
#undef valulng

#ifdef valint
#undef valint
#endif

#ifdef vallng
#undef vallng
#endif

#ifdef valuint
#undef valuint
#endif


#ifdef valulng
#undef valulng
#endif

  
 print cint("12.34")     'uses vallng
 print cuint("12.34")    'uses valulng
 print culng("12.34")    'uses valuint
 print clngint("12.34")  'uses vallng
 print clng("12.34")     'uses valint
 print culngint("12.34") 'uses valulng
 sleep  

Proposed verse:

Change int to long
Change long to int
and to add a final hint . . .
valulng does ulongint

[Munair]

Coming from QuickBASIC I find CInt() much more misleading for string to number conversion as in QB its only function was to round numeric expressions. In this respect Val() is more consistent in that it is traditionally associated with string to number conversion.

[counting_pine]

Cint() in QB wasn’t simply used for mathematical rounding, but for type conversion. It was limited to results between -32768 and 32767. Clng() had a wider type, but still couldn’t convert/round every possible double-precision value.
I agree that val(mid()) is the most familiar way for QB users, but I can’t recommend the habitual use of it in FB, due to its inefficiency. Cint(mid()) may not feel right to a QB veteran, but it’s a better choice for a conversion idiom in FB.

[Munair]

Yes, I forgot to include that QB's CInt in the first place converts numeric expressions to integer.