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Stopwatch Class

Provides a set of methods and properties that you can use to accurately measure elapsed time.

System.Object
  System.Diagnostics.Stopwatch

Namespace:  System.Diagnostics
Assembly:  System (in System.dll)

'Declaration
Public Class Stopwatch

The Stopwatch type exposes the following members.

  NameDescription
Public methodSupported by the XNA FrameworkStopwatchInitializes a new instance of the Stopwatch class.
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  NameDescription
Public propertySupported by the XNA FrameworkElapsedGets the total elapsed time measured by the current instance.
Public propertySupported by the XNA FrameworkElapsedMillisecondsGets the total elapsed time measured by the current instance, in milliseconds.
Public propertySupported by the XNA FrameworkElapsedTicksGets the total elapsed time measured by the current instance, in timer ticks.
Public propertySupported by the XNA FrameworkIsRunningGets a value indicating whether the Stopwatch timer is running.
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  NameDescription
Public methodSupported by the XNA FrameworkEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodSupported by the XNA FrameworkFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodSupported by the XNA FrameworkGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Public methodStatic memberSupported by the XNA FrameworkGetTimestampGets the current number of ticks in the timer mechanism.
Public methodSupported by the XNA FrameworkGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodSupported by the XNA FrameworkMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodSupported by the XNA FrameworkResetStops time interval measurement and resets the elapsed time to zero.
Public methodRestartStops time interval measurement, resets the elapsed time to zero, and starts measuring elapsed time.
Public methodSupported by the XNA FrameworkStartStarts, or resumes, measuring elapsed time for an interval.
Public methodStatic memberSupported by the XNA FrameworkStartNewInitializes a new Stopwatch instance, sets the elapsed time property to zero, and starts measuring elapsed time.
Public methodSupported by the XNA FrameworkStopStops measuring elapsed time for an interval.
Public methodSupported by the XNA FrameworkToStringReturns a string that represents the current object. (Inherited from Object.)
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  NameDescription
Public fieldStatic memberSupported by the XNA FrameworkFrequencyGets the frequency of the timer as the number of ticks per second. This field is read-only.
Public fieldStatic memberSupported by the XNA FrameworkIsHighResolutionIndicates whether the timer is based on a high-resolution performance counter. This field is read-only.
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A Stopwatch instance can measure elapsed time for one interval, or the total of elapsed time across multiple intervals. In a typical Stopwatch scenario, you call the Start method, then eventually call the Stop method, and then you check elapsed time using the Elapsed property.

A Stopwatch instance is either running or stopped; use IsRunning to determine the current state of a Stopwatch. Use Start to begin measuring elapsed time; use Stop to stop measuring elapsed time. Query the elapsed time value through the properties Elapsed, ElapsedMilliseconds, or ElapsedTicks. You can query the elapsed time properties while the instance is running or stopped. The elapsed time properties steadily increase while the Stopwatch is running; they remain constant when the instance is stopped.

By default, the elapsed time value of a Stopwatch instance equals the total of all measured time intervals. Each call to Start begins counting at the cumulative elapsed time; each call to Stop ends the current interval measurement and freezes the cumulative elapsed time value. Use the Reset method to clear the cumulative elapsed time in an existing Stopwatch instance.

The Stopwatch measures elapsed time by counting timer ticks in the underlying timer mechanism. If the installed hardware and operating system support a high-resolution performance counter, then the Stopwatch class uses that counter to measure elapsed time. Otherwise, the Stopwatch class uses the system timer to measure elapsed time. Use the Frequency and IsHighResolution fields to determine the precision and resolution of the Stopwatch timing implementation.

The Stopwatch class assists the manipulation of timing-related performance counters within managed code. Specifically, the Frequency field and GetTimestamp method can be used in place of the unmanaged Win32 APIs QueryPerformanceFrequency and QueryPerformanceCounter.

NoteNote

On a multiprocessor computer, it does not matter which processor the thread runs on. However, because of bugs in the BIOS or the Hardware Abstraction Layer (HAL), you can get different timing results on different processors. To specify processor affinity for a thread, use the ProcessThread.ProcessorAffinity method.

The following example demonstrates how to use the Stopwatch class to determine the execution time for an application.


Imports System
Imports System.Diagnostics
Imports System.Threading


Class Program

    Shared Sub Main(ByVal args() As String)
        Dim stopWatch As New Stopwatch()
        stopWatch.Start()
        Thread.Sleep(10000)
        stopWatch.Stop()
        ' Get the elapsed time as a TimeSpan value.
        Dim ts As TimeSpan = stopWatch.Elapsed

        ' Format and display the TimeSpan value.
        Dim elapsedTime As String = String.Format("{0:00}:{1:00}:{2:00}.{3:00}", ts.Hours, ts.Minutes, ts.Seconds, ts.Milliseconds / 10)
        Console.WriteLine( "RunTime " + elapsedTime)

    End Sub 'Main
End Class 'Program


The following example demonstrates the use of the Stopwatch class to calculate performance data.


Imports System
Imports System.Diagnostics

Class OperationsTimer

   Public Shared Sub Main()
      DisplayTimerProperties()

      Console.WriteLine()
      Console.WriteLine("Press the Enter key to begin:")
      Console.ReadLine()
      Console.WriteLine()

      TimeOperations()
   End Sub


   Public Shared Sub DisplayTimerProperties()

      ' Display the timer frequency and resolution.
      If Stopwatch.IsHighResolution Then
         Console.WriteLine("Operations timed using the system's high-resolution performance counter.")
      Else
         Console.WriteLine("Operations timed using the DateTime class.")
      End If

      Dim frequency As Long = Stopwatch.Frequency
      Console.WriteLine("  Timer frequency in ticks per second = {0}", frequency)
      Dim nanosecPerTick As Long = 1000000000 / frequency
      Console.WriteLine("  Timer is accurate within {0} nanoseconds", nanosecPerTick)

   End Sub

   Private Shared Sub TimeOperations()

      Dim nanosecPerTick As Long = 1000000000 / Stopwatch.Frequency
      Const numIterations As Long = 10000

      ' Define the operation title names.
      Dim operationNames As String() =  _
        {"Operation: Int32.Parse(""0"")", _
         "Operation: Int32.TryParse(""0"")", _
         "Operation: Int32.Parse(""a"")", _
         "Operation: Int32.TryParse(""a"")"}

      ' Time four different implementations for parsing 
      ' an integer from a string. 

      Dim operation As Integer
      For operation = 0 To 3
         ' Define variables for operation statistics.
         Dim numTicks As Long = 0
         Dim numRollovers As Long = 0
         Dim maxTicks As Long = 0
         Dim minTicks As Long = Int64.MaxValue
         Dim indexFastest As Integer = - 1
         Dim indexSlowest As Integer = - 1
         Dim milliSec As Long = 0

         Dim time10kOperations As Stopwatch = Stopwatch.StartNew()

         ' Run the current operation 10001 times.
         ' The first execution time will be tossed
         ' out, since it can skew the average time.
         Dim i As Integer
         For i = 0 To numIterations
            Dim ticksThisTime As Long = 0
            Dim inputNum As Integer
            Dim timePerParse As Stopwatch

            Select Case operation
               Case 0
                  ' Parse a valid integer using
                  ' a try-catch statement.
                  ' Start a new stopwatch timer.
                  timePerParse = Stopwatch.StartNew()

                  Try
                     inputNum = Int32.Parse("0")
                  Catch e As FormatException
                     inputNum = 0
                  End Try

                  ' Stop the timer, and save the
                  ' elapsed ticks for the operation.
                  timePerParse.Stop()
                  ticksThisTime = timePerParse.ElapsedTicks
               Case 1
                  ' Parse a valid integer using
                  ' the TryParse statement.
                  ' Start a new stopwatch timer.
                  timePerParse = Stopwatch.StartNew()

                  If Not Int32.TryParse("0", inputNum) Then
                     inputNum = 0
                  End If

                  ' Stop the timer, and save the
                  ' elapsed ticks for the operation.
                  timePerParse.Stop()
                  ticksThisTime = timePerParse.ElapsedTicks
               Case 2
                  ' Parse an invalid value using
                  ' a try-catch statement.
                  ' Start a new stopwatch timer.
                  timePerParse = Stopwatch.StartNew()

                  Try
                     inputNum = Int32.Parse("a")
                  Catch e As FormatException
                     inputNum = 0
                  End Try

                  ' Stop the timer, and save the
                  ' elapsed ticks for the operation.
                  timePerParse.Stop()
                  ticksThisTime = timePerParse.ElapsedTicks
               Case 3
                  ' Parse an invalid value using
                  ' the TryParse statement.
                  ' Start a new stopwatch timer.
                  timePerParse = Stopwatch.StartNew()

                  If Not Int32.TryParse("a", inputNum) Then
                     inputNum = 0
                  End If

                  ' Stop the timer, and save the
                  ' elapsed ticks for the operation.
                  timePerParse.Stop()
                  ticksThisTime = timePerParse.ElapsedTicks

               Case Else
            End Select

            ' Skip over the time for the first operation,
            ' just in case it caused a one-time
            ' performance hit.
            If i = 0 Then
               time10kOperations.Reset()
               time10kOperations.Start()
            Else

               ' Update operation statistics
               ' for iterations 1-10001.
               If maxTicks < ticksThisTime Then
                  indexSlowest = i
                  maxTicks = ticksThisTime
               End If
               If minTicks > ticksThisTime Then
                  indexFastest = i
                  minTicks = ticksThisTime
               End If
               numTicks += ticksThisTime
               If numTicks < ticksThisTime Then
                  ' Keep track of rollovers.
                  numRollovers += 1
               End If
            End If
         Next i

         ' Display the statistics for 10000 iterations.
         time10kOperations.Stop()
         milliSec = time10kOperations.ElapsedMilliseconds

         Console.WriteLine()
         Console.WriteLine("{0} Summary:", operationNames(operation))
         Console.WriteLine("  Slowest time:  #{0}/{1} = {2} ticks", _
            indexSlowest, numIterations, maxTicks)
         Console.WriteLine("  Fastest time:  #{0}/{1} = {2} ticks", _
            indexFastest, numIterations, minTicks)
         Console.WriteLine("  Average time:  {0} ticks = {1} nanoseconds", _
            numTicks / numIterations, numTicks * nanosecPerTick / numIterations)
         Console.WriteLine("  Total time looping through {0} operations: {1} milliseconds", _
            numIterations, milliSec)
      Next operation

   End Sub
End Class


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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