• Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 1681
  • Last Modified:

Calculate datediff using SystemTime

I need to calculate the difference in times down to the milliSecond.
DateDiff won't accept SystemTime so I wanted a native function to calc datediff down to the ms.

Thanks
0
sidwelle
Asked:
sidwelle
  • 3
  • 2
  • 2
  • +1
1 Solution
 
zorvek (Kevin Jones)ConsultantCommented:
If you are looking for the delta time between two points in your code use the VB Timer function. it returns a Single representing the number of seconds elapsed since midnight. It is accurate down to about 1/100 of a second.

Kevin
0
 
Jaime OlivaresSoftware ArchitectCommented:
if you just want the difference in miliseconds, you can use the WinAPI GetTickCount()
0
 
Jaime OlivaresSoftware ArchitectCommented:
Declare Function GetTickCount Lib "kernel32" () As Long

Dim t0 as Long
Dim t1 as Long
Dim diff as Long

    t0 = GetTickCount()
    ' Do some task here
    t1 = GetTickCount()

diff = t1 - t0   ' difference in miliseconds
0
Cloud Class® Course: SQL Server Core 2016

This course will introduce you to SQL Server Core 2016, as well as teach you about SSMS, data tools, installation, server configuration, using Management Studio, and writing and executing queries.

 
zorvek (Kevin Jones)ConsultantCommented:
The Windows SDK function GetTickCount has the same accuracy as the VB Timer function. I believe the Timer function uses GetTickCount.

Kevin
0
 
zorvek (Kevin Jones)ConsultantCommented:
Here is a short article on getting better timing on Windows using VB and VB.net:

http://gpwiki.org/index.php/VB:Timers

Also note the following:

Windows NT 3.5 and later The system timer runs at approximately 10ms.
Windows NT 3.1 The system timer runs at approximately 16ms.
Windows 95 and later The system timer runs at approximately 55ms.

Kevin
0
 
PaulHewsCommented:
Find difference in milliseconds between two systemtime variables:


Private Function GetDiffMilliseconds(Second As SYSTEMTIME, First As SYSTEMTIME) As Long
    'This function assumes the second date is the greater in'
    'order to return positive number differences.'
    'Returns number of milliseconds difference.
    
    Dim Ret As Long
    Dim dtFirst As Date, dtSecond As Date
    
    dtFirst = DateSerial(First.wYear, First.wMonth, First.wDay) + TimeSerial(First.wHour, First.wMinute, First.wSecond)
    dtSecond = DateSerial(First.wYear, First.wMonth, First.wDay) + TimeSerial(First.wHour, First.wMinute, First.wSecond)
 
    Ret = Second.wMilliseconds - First.wMilliseconds
    Ret = DateDiff("s", dtFirst, dtSecond) * 1000 + Ret
 
 
    GetDiffMilliseconds = Ret
End Function

Open in new window

0
 
PaulHewsCommented:
Woops, a couple of fixes.... Fix a typo and an overflow problem.
Private Function GetDiffMilliseconds(Second As SYSTEMTIME, First As SYSTEMTIME) As Double
    'This function assumes the second date is the greater in'
    'order to return positive number differences.'
    'Returns number of milliseconds difference.'
    
    Dim Ret As Double
    Dim dtFirst As Date, dtSecond As Date
    
    dtFirst = DateSerial(First.wYear, First.wMonth, First.wDay) + TimeSerial(First.wHour, First.wMinute, First.wSecond)
    dtSecond = DateSerial(Second.wYear, Second.wMonth, Second.wDay) + TimeSerial(Second.wHour, Second.wMinute, Second.wSecond)
 
    Ret = Second.wMilliseconds - First.wMilliseconds
    Ret = DateDiff("s", dtFirst, dtSecond) * CDbl(1000) + Ret
 
 
    GetDiffMilliseconds = Ret
End Function

Open in new window

0
 
sidwelleAuthor Commented:
Thanks Paul,
0
Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

Join & Write a Comment

Featured Post

Cloud Class® Course: CompTIA Cloud+

The CompTIA Cloud+ Basic training course will teach you about cloud concepts and models, data storage, networking, and network infrastructure.

  • 3
  • 2
  • 2
  • +1
Tackle projects and never again get stuck behind a technical roadblock.
Join Now