C# Stopwatch Explained – How to Measure Code Execution Time?

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C# Stopwatch is a powerful class provided by the .NET Framework that we can use to measure the execution time of a specific code block.
It is commonly used in performance testing and benchmarking applications to measure the time a code snippet takes to execute.

The Stopwatch class is part of the System.Diagnostics namespace and is available in all .NET programming languages, including C#.

csharp-stopwatch
C# Stopwatch

Syntax: 

The syntax for creating a Stopwatch object is as follows:

Stopwatch stopwatch = new Stopwatch();

Example:

Here is an example of how to use the Stopwatch class in C#:

using System;
using System.Diagnostics;
public class Program
{
    public static void Main()
    {
        // Example usage of the Measure method
        Console.WriteLine("Method 1");
        Measure(() => Method1());
        Console.WriteLine("Method 2");
        Measure(() => Method2());
        
        Console.ReadKey();
    }

    public static void Measure(Action action)
    {
        Stopwatch stopwatch = new Stopwatch();
        stopwatch.Start();
        action();
        stopwatch.Stop();
        Console.WriteLine($"Execution time: {stopwatch.ElapsedMilliseconds} ms");
    }

    public static void Method1()
    {
        // Code to be measured
        for (int i = 0; i < 1000000; i++)
        {
            int x = i + i;
        }
    }

    public static void Method2()
    {
        // Code to be measured
        for (int i = 0; i < 10000000; i++)
        {
            int x = i * i;
        }
    }
}

Output:

C# Stopwatch example
C# Stopwatch example

Stopwatch Methods

The Stopwatch class provides various methods to control the stopwatch and retrieve the elapsed time.

Here are some of the important methods:

MethodDescription
Start():Starts the stopwatch.
Stop():Stops the stopwatch.
Reset():Resets the stopwatch to its initial state.
Restart():Restart the stopwatch.
StartNew():The StartNew() method initializes a fresh instance of the Stopwatch class, sets the elapsed time property to zero, and begins measuring the duration of elapsed time.
GetTimestamp():The method GetTimestamp() retrieves the current tick count from the timer mechanism.

Stopwatch Properties/Fields

In addition to the methods, the Stopwatch class provides properties that can retrieve information about the stopwatch. Here are some of the important properties:

PropertyDescription
Frequency:Gets the frequency of the timer as the number of ticks per second.
IsHighResolution:Gets a value indicating whether the timer is based on a high-resolution performance counter.
Elapsed:Gets the total elapsed time measured by the current instance.
ElapsedMilliseconds:Gets the total elapsed time measured by the current instance in milliseconds.
ElapsedTicks:Gets the total elapsed time measured by the current instance in timer ticks.
IsRunning:The IsRunning property of the Stopwatch class indicates whether the timer is currently active or not. It returns a boolean value that is true if the timer is running and false if it has been stopped.

Using the IsHighResolution Property of Stopwatch

IsHighResolution property of the Stopwatch class checks if high-resolution timing is supported on the system. We can measure the execution time of an operation with high accuracy using the ElapsedTicks property and the system’s performance counter frequency. 

If high-resolution timing is not supported, the Stopwatch class returns to using the system’s standard timer, which has a lower resolution and may not provide accurate timing measurements.

Example:

using System;
using System.Diagnostics;

class Program
{
    static void Main()
    {
        Stopwatch stopwatch = new Stopwatch();
        if (Stopwatch.IsHighResolution)
        {
            stopwatch.Start();

            // Perform operation

            stopwatch.Stop();

            // Get elapsed time in ticks
            long elapsedTicks = stopwatch.ElapsedTicks;
            double elapsedNanoseconds = (double)elapsedTicks / Stopwatch.Frequency * 1000000000;
            Console.WriteLine($"Time taken: {elapsedNanoseconds} ns");
        }
        else
        {
            Console.WriteLine("High-resolution timing is not supported on this system.");
        }
        Console.ReadKey();


    }
}

Output:

Time taken: 6000 ns

Please note that the output may vary when running the code on different systems or under different conditions.

Using the Restart() Method to Measure Multiple Operations

When measuring the execution time of multiple operations, you should restart the Stopwatch object instead of creating a new one for each operation. The Restart() method resets the elapsed time and starts the Stopwatch again. Here is an example:

using System;
using System.Diagnostics;

public class Program
{
    public static void Main()
    {
        Stopwatch stopwatch = new Stopwatch();

        // First operation to measure
        stopwatch.Start();
        Method1();
        stopwatch.Stop();
        Console.WriteLine($"Execution time for Method1: {stopwatch.ElapsedMilliseconds} ms");

        // Second operation to measure
        stopwatch.Restart();
        Method2();
        stopwatch.Stop();
        Console.WriteLine($"Execution time for Method2: {stopwatch.ElapsedMilliseconds} ms");

        Console.ReadKey();
    }

    public static void Method1()
    {
        // Code for first operation
        for (int i = 0; i < 1000000; i++)
        {
            int x = i + i;
        }
    }

    public static void Method2()
    {
        // Code for second operation
        for (int i = 0; i < 10000000; i++)
        {
            int x = i * i;
        }
    }
}

Output:

Stopwatch in CSarp example
Stopwatch example

Refrences:Msdn – C# Stopwatch

FAQs

Q: What is a Stopwatch in C#?

A Stopwatch class in C# provides a high-resolution timer to measure elapsed time for code execution or other operations.

Q: How do I use the Stopwatch class in C#?

To use the Stopwatch class, you must create a new class instance. You can then call the Start method to start the timer and the Stop method to stop the timer and measure the elapsed time.

Q: What is the resolution of the Stopwatch class in C#?

The resolution of the Stopwatch class depends on the system hardware and operating system. It typically has a resolution of around 1 nanosecond.

Q: What is the difference between Elapsed and ElapsedMilliseconds properties in the Stopwatch class?

The Elapsed property returns the elapsed time as a TimeSpan object, which provides more precision than the ElapsedMilliseconds property, which returns the elapsed time as a long integer in milliseconds.

Q: Can you use the Stopwatch class to measure the performance of my code?

Yes, the Stopwatch class is often used to measure code performance and identify areas that can be optimized for better performance.

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Shekh Ali
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