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Stopwatch.Start Method

Starts, or resumes, measuring elapsed time for an interval.

Namespace:  System.Diagnostics
Assemblies:   System (in System.dll)
  System.Runtime.Extensions (in System.Runtime.Extensions.dll)

public void Start()

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.

Once started, a Stopwatch timer measures the current interval, in elapsed timer ticks, until the instance is stopped or reset. Starting a Stopwatch that is already running does not change the timer state or reset the elapsed time properties.

When a Stopwatch instance measures more than one interval, the Start method resumes measuring time from the current elapsed time value. A Stopwatch instance calculates and retains the cumulative elapsed time across multiple time intervals, until the instance is reset. Use the Reset method before calling Start to clear the cumulative elapsed time in a Stopwatch instance. Use the Restart method to Reset and Start the Stopwatch with a single command.

The following example demonstrates how to use the Start method to start a timer that measures the execution time of an application.

using System;
using System.Diagnostics;
using System.Threading;
class Program
{
    static void Main(string[] args)
    {
        Stopwatch stopWatch = new Stopwatch();
        stopWatch.Start();
        Thread.Sleep(10000);
        stopWatch.Stop();
        // Get the elapsed time as a TimeSpan value.
        TimeSpan ts = stopWatch.Elapsed;

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

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Portable Class Library

Supported in: Portable Class Library
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