task in constructor c#

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Task Constructors

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Initializes a new Task .

Task(Action)

Initializes a new Task with the specified action.

The delegate that represents the code to execute in the task.

The action argument is null .

The following example uses the Task(Action) constructor to create tasks that retrieve the filenames in specified directories. All tasks write the file names to a single ConcurrentBag<T> object. The example then calls the WaitAll(Task[]) method to ensure that all tasks have completed, and then displays a count of the total number of file names written to the ConcurrentBag<T> object.

The following example is identical, except that it used the Run(Action) method to instantiate and run the task in a single operation. The method returns the Task object that represents the task.

This constructor should only be used in advanced scenarios where it is required that the creation and starting of the task is separated.

Rather than calling this constructor, the most common way to instantiate a Task object and launch a task is by calling the static Task.Run(Action) or TaskFactory.StartNew(Action) method.

If a task with no action is needed just for the consumer of an API to have something to await, a TaskCompletionSource<TResult> should be used.

• Run(Action)

Task(Action, CancellationToken)

Initializes a new Task with the specified action and CancellationToken .

The CancellationToken that the new task will observe.

The provided CancellationToken has already been disposed.

The action argument is null.

The following example calls the Task(Action, CancellationToken) constructor to create a task that iterates the files in the C:\Windows\System32 directory. The lambda expression calls the Parallel.ForEach method to add information about each file to a List<T> object. Each detached nested task invoked by the Parallel.ForEach loop checks the state of the cancellation token and, if cancellation is requested, calls the CancellationToken.ThrowIfCancellationRequested method. The CancellationToken.ThrowIfCancellationRequested method throws an OperationCanceledException exception that is handled in a catch block when the calling thread calls the Task.Wait method. The Start method is then called to start the task.

Rather than calling this constructor, the most common way to instantiate a Task object and launch a task is by calling the static Task.Run(Action, CancellationToken) and TaskFactory.StartNew(Action, CancellationToken) methods. The only advantage offered by this constructor is that it allows object instantiation to be separated from task invocation.

For more information, see Task Parallelism (Task Parallel Library) and Cancellation in Managed Threads .

Task(Action, TaskCreationOptions)

Initializes a new Task with the specified action and creation options.

The TaskCreationOptions used to customize the task's behavior.

The creationOptions argument specifies an invalid value for TaskCreationOptions .

Rather than calling this constructor, the most common way to instantiate a Task object and launch a task is by calling the static TaskFactory.StartNew(Action, TaskCreationOptions) method. The only advantage offered by this constructor is that it allows object instantiation to be separated from task invocation.

Task(Action<Object>, Object)

Initializes a new Task with the specified action and state.

An object representing data to be used by the action.

The following example defines an array of 6-letter words. Each word is then passed as an argument to the Task(Action<Object>, Object) constructor, whose Action<T> delegate scrambles the characters in the word, then displays the original word and its scrambled version.

Rather than calling this constructor, the most common way to instantiate a Task object and launch a task is by calling the static TaskFactory.StartNew(Action<Object>, Object) method. The only advantage offered by this constructor is that it allows object instantiation to be separated from task invocation.

• StartNew(Action<Object>, Object)

Task(Action, CancellationToken, TaskCreationOptions)

The CancellationTokenSource that created cancellationToken has already been disposed.

Rather than calling this constructor, the most common way to instantiate a Task object and launch a task is by calling the static TaskFactory.StartNew(Action, CancellationToken, TaskCreationOptions, TaskScheduler) method. The only advantage offered by this constructor is that it allows object instantiation to be separated from task invocation.

For more information, see Task Parallelism (Task Parallel Library) and Task Cancellation .

Task(Action<Object>, Object, CancellationToken)

Initializes a new Task with the specified action, state, and CancellationToken .

Rather than calling this constructor, the most common way to instantiate a Task object and launch a task is by calling the static TaskFactory.StartNew(Action<Object>, Object, CancellationToken) method. The only advantage offered by this constructor is that it allows object instantiation to be separated from task invocation.

Task(Action<Object>, Object, TaskCreationOptions)

Initializes a new Task with the specified action, state, and options.

Rather than calling this constructor, the most common way to instantiate a Task object and launch a task is by calling the static TaskFactory.StartNew(Action<Object>, Object, TaskCreationOptions) method. The only advantage offered by this constructor is that it allows object instantiation to be separated from task invocation.

Task(Action<Object>, Object, CancellationToken, TaskCreationOptions)

Rather than calling this constructor, the most common way to instantiate a Task object and launch a task is by calling the static TaskFactory.StartNew(Action<Object>, Object, CancellationToken, TaskCreationOptions, TaskScheduler) method. The only advantage offered by this constructor is that it allows object instantiation to be separated from task invocation.

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Additional resources

Home » C# Concurrency » C# Task

Summary : in this tutorial, you’ll learn about the task-based asynchronous pattern (TAP) in C# and how to use the C# Task class to create asynchronous operations.

Introduction to the task-based asynchronous pattern (TAP)

C# introduced an asynchronous programming model (APM) that provides a way to perform I/O bound operations asynchronously.

The APM is based on callback concepts:

• A method that represents an asynchronous operation that accepts a callback.
• When the asynchronous operation completes, the method invokes the callback to notify the calling code.

Because APM is quite difficult to understand, C# introduced the event-based asynchronous pattern (EAP) that performs asynchronous operations using events.

Unlike the APM, in EAP, the method raises an event when the asynchronous operation completes instead of calling a callback.

EAP is easier to use and has better error handling than the APM. However, EAP is quite complex to use.

To solve this issue, C# introduced task-based asynchronous programming (TAP) that greatly simplifies asynchronous programming and makes it easier to write asynchronous code.

TAP consists of the following key components:

• The Task class – represents an asynchronous operation.
• The async / await keywords – define asynchronous methods and wait for the completion of asynchronous operations.
• Task-based API – a set of classes that work seamlessly with the Task class and async/await keywords.

TAP has the following advantages:

• Improved performance – TAP can improve an application’s performance by allowing it to perform I/O-bound operations asynchronously, freeing up the CPU for other tasks.
• Simplified code – TAP allows you to write asynchronous code like synchronous code that makes it easy to understand.
• Better resource management – TAP optimizes system resources by allowing applications to perform asynchronous operations without blocking threads.

In this tutorial, we’ll focus on the Task class, and how to use it to execute asynchronous operations.

The Task class

The Task class is a core concept of the TAP. It represents an asynchronous operation that can be executed in various ways.

Suppose you have a method that performs an asynchronous operation called GetRandomNumber() that returns a random number between 1 and 100 like this:

Unlike a regular function, the GetRandomNumber() uses the Thread.Sleep () to delay one second before returning a random number. The purpose of the Thread.Sleep() is to simulate an asynchronous operation that takes about one second to complete.

Running a task

To execute the GetRandomNumber() method asynchronously, you create a new Task object and call the GetRandomNumber() method in a lambda expression passed to the Task ‘s constructor:

and start executing the task by calling the Start() method of the Task object:

Put it all together:

Note that the task.Start () method doesn’t block the main thread therefore you see the following message first:

….before the random number:

The Console.ReadLine() blocks the main thread until you press a key. It is used for waiting for the child thread scheduled by the Task object to complete.

If you don’t block the main thread, it’ll be terminated after the program displays the message “Start the program…”.

Notice that the Task constructor accepts many other options that you don’t need to worry about for now.

Behind the scenes, the program uses a thread pool for executing the asynchronous operation. The Start() method schedules the operation for execution.

To prove this, we can display the thread id and whether or not the thread belongs to the managed thread pool:

The output shows that the thread id is 5 and the thread belongs to a thread pool. Note that you likely see a different number.

Since the code for creating a Task object and starting it are quite verbose, you can shorten it by using the Run() static method of the Task class:

The Run() method queues operation ( GetRandomNumber ) to the thread pool for execution.

Similarly, you can use the StartNew() method of the Factory object of the Task class to create a new task and schedule its execution:

Getting the result from a task

The Run() method returns a Task< TResult > object that represents the result of the asynchronous operation.

In our example, the GetRandomNumber() returns an integer, therefore, the Task.Run () returns the Task<int> object:

To get the returned number of the GetRandomNumber() method, you use the Result property of the task object:

Put it all together.

• Use task-based asynchronous programming (TAP) for developing asynchronous programs.
• Use the Task class to execute asynchronous operations.

A Tour of Task, Part 1: Constructors

TL;DR: Do not use Task or Task<T> constructors.

I actually debated quite a bit on how to start this series! I finally decided on starting with the constructors, even though the Task constructors are a red herring.

The Task type has a whopping eight constructors:

The BCL avoids default parameters because they don’t work well with versioning and reflection. However, I’m going to rewrite some of the members with optional parameters to reduce the number of overloads that I need to talk about.

I’m going to call the eight constructors “actual members” because they actually exist. However, these can be reduced to only one “logical member”:

Similarly, the Task<T> type has eight actual constructors:

Which simplify down to a single logical constructor:

So, we have 16 actual constructors and two logical constructors.

The use case for the task constructors is extremely small.

Remember that there are two kinds of tasks: Promise Tasks and Delegate Tasks. The task constructors cannot create Promise Tasks; they only create Delegate Tasks.

Task constructors should not be used with async , and they should only rarely be used with parallel programming.

Parallel programming can be split into two types: data parallelism and task parallelism, with the majority of parallel situations calling for data parallelism. Task parallelism can be further split into two types: static task parallelism (where the number of work items is known at the beginning of the parallel processing) and dynamic task parallelism (where the number of work items changes while they are being processed). The Parallel class and PLINQ types in the Task Parallel Library provide higher-level constructs for dealing with data parallelism and static task parallelism. The only reason you should ever create a Delegate Task for parallel code is if you are doing dynamic task parallelism. But even then, you almost never want to use the task constructors! The task constructors create a task that is not ready to run; it has to be scheduled first. This is almost never necessary; in the real world, most tasks should be scheduled immediately. The only reason you’d want to create a task and then not schedule it is if you wanted to allow the caller to determine which thread the task actually runs on. And even in that scenario, I’d recommend using Func<Task> instead of returning an unscheduled task.

Let me put that another way: if you are doing dynamic task parallelism and need to construct a task that can run on any thread, and leave that scheduling decision up to another part of the code, and for whatever reason cannot use Func<Task> instead, then (and only then) you should use a task constructor. I’ve written countless asynchronous and parallel applications, and I have never been in this situation.

Even shorter version: Do Not Use!

What Instead?

If you’re writing async code, the easiest way to create a Promise Task is to use the async keyword. If you’re wrapping another asynchronous API or event, use Task.Factory.FromAsync or TaskCompletionSource<T> . If you need to run some CPU-bound code and treat it asynchronously, use Task.Run . We’ll look at all of these options and more in future posts.

If you’re writing parallel code, first try to use Parallel or PLINQ . If you actually are doing dynamic task parallelism, use Task.Run or Task.Factory.StartNew . We’ll consider these options as well in future posts.

Sorry that the first post just boiled down to “don’t use this”, but it is what it is. I’ll cover all the constructor arguments such as CancellationToken later when I cover Task.Factory.StartNew .

• Constructors
• AsyncState and CreationOptions
• Continuations
• Delegate Tasks
• Promise Tasks

• Async/await Intro
• There Is No Thread
• Don't Block on Async Code
• React/Redux TodoMVC
• A Tour of Task
• Task.Run Etiquette
• Task.Run vs. BackgroundWorker
• TCP/IP .NET Sockets FAQ
• Managed Services
• IDisposable and Finalizers
• Option Parsing

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Lazy and once-only C# async initialization

There are a couple of closely related optimizations that are often useful: lazy initialization, and "just once" initialization. These are conceptually pretty straightforward, although the details can get messy once multiple threads are involved. But what if the initialization work involves asynchronous operation?

Lazy initialization

Lazy initialization is an important performance technique. Putting off work until you know you need the results enables you to get on with more useful things in the meantime. And, once you've done the work, hanging onto the results may save you from repeating that work later. It's a pretty simple concept, but in multi-threaded environments it's surprisingly easy to get it wrong, and so .NET provides some helper types that handle the subtle race conditions for you: Lazy<T> and LazyInitializer . (The latter is more lightweight, but uses an optimistic concurrency policy that means it will occasionally execute your initialization code twice, and then discard one of the results. If you can't tolerate this, use Lazy<T> .)

Just-once initialization

Lazy initialization incorporates a simpler idea that we could use in isolation: if you're going to do some expensive work, better to do it just once, instead of repeating it every time you need the results of that work. This idea is so simple that it might seem like it barely needs stating, but once you add in concurrency, it is the reason lazy initialization is surprisingly easy to get wrong.

Lazy<T> gives us just-once initialization, but what if we only want the just-once behaviour, and don't require laziness? Perhaps there's some work that our program is inevitably going to need to perform, so there's no particular benefit in deferring it, but we still want the just-once behaviour.

That shouldn't be so hard, right? We could do that in the constructor:

There is one objection to this: some take the view that constructors shouldn't do non-trivial work. However, I'm not going to be dogmatic about that. Instead, I want to look at a variation on this: what if the slow work we need to perform just once involves asynchronous operation?

Async just-once eager initialization

If PerformSlowWork in the preceding example returned Task<T> , the simple approach I just showed won't work. Constructors cannot be declared as async (because they can't return a Task —by definition they return an instance of the type they construct). We might be tempted to do this:

Don't do that.

In general, it's a really bad idea to retrieve the Result of a Task<T> unless you can be certain that the task has already completed (which it almost certainly won't have done in this example). There are a handful of exceptions to that rule, but they are specialized and tricky to get right. Unless you are in complete control of the context in which it runs, using Result in the way shown above risks causing a deadlock. (Reading Result on an unfinished task blocks the calling thread, and if the thread has ownership of anything required to complete the asynchronous work, that will prevent completion.)

However, there is a pretty simple way to get the same effect safely:

Since in this scenario we know we will definitely need to perform the slow work, we don't need lazy behaviour, so we kick the work off immediately in the constructor. But we don't wait for it to finish there—we just store the resulting task. And then, any method that needs access to that expensive-to-obtain information can just await that task.

This works because you are allowed to await the same Task<T> any number of times. (Note that the field has to be a Task<T> , not a ValueTask<T> . You're only allowed to await a ValueTask<T> once.) Calls to DoSomethingAsync that occur before the expensive work is complete will block at the await . If there are multiple concurrent calls to the method while we're in that state, that's fine, they'll all just block, and then when the expensive initialization completes, they will all become runnable simultaneously. (Whether they actually run concurrently at that point will typically be down to the task scheduler, which by default will defer to the thread pool.)

In a program that expects to call that DoSomethingAsync method many times in succession, we would expect the first call to be slow (because it will have to wait for the expensive asynchronous initialization to complete) but subsequent calls will not have to wait because that data task will have completed, so the await won't need to wait. This is why I've made DoSomethingAsync return a ValueTask<string> . Asynchronous methods that you expect mostly not to need to block in practice are more memory-efficient if they return a ValueTask<string> .

Async lazy initialization

The eager asynchronous initialization just shown is good if you know you're definitely going to need the results of the work, and are likely to need it as early as possible. But in cases where your code might not need the results at all (e.g., you're writing a command line tool, and only certain command line flags will trigger the behaviour that needs this particular data), then lazy initialization is a better bet.

These Lazy<T> and LazyInitializer types mentioned earlier do not offer any direct support for asynchronous code. That's essentially because they don't need to. You can just use Lazy<Task<T>> , e.g.:

This avoids starting the expensive work until something asks for it. So this will give you "at most once" initialization—if the program never hits the code path that asks for the results of this expensive work, it will never be performed. But once something does ask, Lazy<T> will ensure that it only runs the code that builds the Task<T> once.

What if your organization tolerates failure?

Although Blofeld might not approve, sometimes it is necessary to tolerate failure. The problem with the async techniques just shown is that if the initialization fails, you are stuck with Task<T> that is in a faulted state, so every attempt to await it will throw an exception. To be able to recover from this, you would need to be able to reset the field.

Here's one way you could do that:

In practice, error recovery behaviour is often application-specific, so you might need something more complex. But the basic idea of creating a new Lazy<Task<T>> (or new Task<T> if you need just-once but don't care about laziness) will remain.

There's no specific support in .NET for lazy or once-only initialization, but you don't need it. A field of type Lazy<Task<T>> will do the job. And if you don't need the lazy part, you can get once-only async initialization by storing just a Task<T> in a field.

Also worth reading:

Retrying tasks with TPL, async and synchronous code

Matthew adams 23/05/2013.

An Overview of the Corvus.Retry Library

Liam mooney 14/12/2022.

Async pitfalls: deferred work and resource ownership

Ian griffiths 21/09/2018, ian griffiths, technical fellow i.

Ian has worked in various aspects of computing, including computer networking, embedded real-time systems, broadcast television systems, medical imaging, and all forms of cloud computing. Ian is a Technical Fellow at endjin, and Microsoft MVP in Developer Technologies. He is the author of O'Reilly's Programming C# 10.0 , and has written Pluralsight courses on WPF ( and here ) and the TPL . He's a maintainer of Reactive Extensions for .NET , Reaqtor , and endjin's 50+ open source projects . Technology brings him joy.

Constructors in C#

Back to: C#.NET Tutorials For Beginners and Professionals

Constructors in C# with Examples

In this article, I am going to discuss Constructors in C# with Examples. Please read our previous article before proceeding to this article where we discussed how to create classes and objects in C# with examples. Object-Oriented Programming is all about writing code inside a class. A class is a collection of members like fields, methods, constructors, etc. Inside a class one of the most important members present is called Constructor.

What is a Constructor in C#?

It is a special method present inside a class responsible for initializing the variables of that class. We will come to this point later part of this article.

The name of the constructor method is exactly the same name as the class in which it was present. You cannot change the name. If your class name is Employee, then the name of the constructor method is going to be Employee, and if your class name is Student, then the constrictor name is also going to be Student.

The constructor method does not return any value. That means it is a non-value returning method. Generally, methods are of two types i.e. value returning and non-value returning and constructors are purely non-value returning. That is, they never return any value.

Example to Understand Constructor in C#

Each and every class requires this constructor if we want to create the instance of the class. If we don’t have a constructor, then we cannot create an instance of the class. At this point, you have one doubt, earlier we defined many classes but we never used a constructor, but still, we are able to create the instance of the class, how? Let us clarify this doubt. Suppose, we have a class as follows:

Then, we create an instance of the above Test class somewhere in our application as follows:

Test obj = new Test();

Is the above statement valid? Yes, it is valid. The reason is that it is the responsibility of a programmer to define a constructor under his class and if he/she fails to do, on behalf of the programmer an implicit constructor gets defined in that class by the compiler. For a better understanding, please have a look at the below diagram which shows the code before and after compilation.

You can see here that after compilation, the compiler adds the public constructor to the class and initializes the variable and this is the responsibility of a constructor i.e. initializing the variables of that class. Here, it is initializing the variable with 0. If a class variable is initialized implicitly means that is done by a constructor.

Every variable we declared inside a class and every field we declared inside a class has a default value. All numeric types are initialized with 0, Boolean types initialized with false, and string and object types initialized with null. For a better understanding, please have a look at the below image.

Like this, the initialization is performed for each and all variables present in the class and this is the responsibility of the constructor. That is why a constructor is very important for us inside a class.

We are not assigning a value, but a value is coming there means someone has assigned the value to these variables. So, who is going to do that? The constructor is going to do that. And this constructor is not defined by us. Then who defined this constructor? The compiler defined this constructor for us. And we call this an Implicit Constructor. And if we defined the same thing, then it is called an explicit constructor.

Points to Remember while working with Constructors in C#:

• Implicitly Defined Constructors are parameter less and these constructors are also known as Default Constructors. This is because they are used to initialize the variables with default values.
• Implicitly Defined Constructors are public. If you see in our example, we define the class Test with a default access specifier but the constructor is public which is generated by the compiler.
• We can also define a constructor under the class and if we define it, we can call it an Explicit Constructor and an Explicit Constructor can be parameter less and parameterized also.

Example to Understand Implicitly Constructor in C#:

In the below example, we are creating a class with three variables and in the class, we have not defined any constructor explicitly. So, here compiler will provide the implicit constructor and will initialize the variables with the default value. Then from the Main method, we create an instance of the class and print the values of the variables and it should print the default values based on the variable type. For example, for int, the default value is 0, for bool the default value is false, and for string or object the default is null. And this default initialization is done by the implicit constructor which is given by the compiler.

How to Define the Constructor Explicitly in C#?

We can also define the constructor explicitly in C#. The following is the explicit constructor syntax.

Whenever we are creating an instance, there will be a call to the class constructor. For a better understanding, please have a look at the below example. Here, we defined one parameter less constructor explicitly, and then from the Main method, we create an instance. When we create the instance, it will make a call to the constructor, and the statements written inside the constructor will be executed. In this case, it will execute the print statement in the console.

Output: Explicit Constructor is Called!

One more important point that you need to remember is, how many instances you created, and that many times the constructor is called for us. Let us prove this. Please modify the example code as follows. Here, I am creating the instance four times and it should and must call the constructor 4 times and we should see the print statement four times in the console window.

We should not use the word Implicitly while calling the constructor in C#, why?

See, if we are not defining any constructor explicitly, then the compiler will provide the constructor which is called Implicitly Constructor. See, the following example. If you move the mouse pointer over the Test class, then you will see the following. Here, Test is a class present under the ConsructorDemo namespace.

Now, move the mouse pointer to Test() as shown in the below image. Here, the first Test is the class name and the second Test() is the constructor. That means we are calling the constructor explicitly.

Here, we are explicitly making a call to the constructor and when we call the constructor, the implicit constructor which is provided by the compiler is called and will initialize the variables.

Now coming to the ExplicitConstructor example, we are also doing the same thing. Please have a look at the below example. If you move the mouse pointer over the ExplicitConstructor class, then you will see the following. Here, ExplicitConstructor is a class present under the ConsructorDemo namespace.

Now, move the mouse pointer to ExplicitConstructor() as shown in the below image. Here, the first ExplicitConstructor is the class name and the second ExplicitConstructor() is the constructor. That means we are calling the constructor explicitly.

Here, we are explicitly making a call to the constructor and when we call the constructor, the explicit constructor which is provided by us is called and will initialize the variables. So, here you might be confused with terms. Defining and calling.

Defining and Calling Constructor in C#:

Defining: Defining a constructor means implementing a constructor in your class. Defining can be two types i.e. Implicit and Explicit. Implicit means the compiler will define the constructor. Explicit means we as a programmer define the constructor. The following code shows defining a constructor explicitly.

Calling: Whenever we are creating the instance, we are calling the constructor. Calling is Explicit. We should only call. There is no implicit call to the constructor. For a better understanding, please have a look at the below code.

The calling should be done explicitly by us. That may be an implicit or explicit constructor but calling the constructor should be explicit.

Frequently Asked Interview Questions:

In simple words, we can define the constructors in C# are the special types of methods of a class that are executed whenever we create an instance (object) of that class. The Constructors are responsible for two things. One is the object initialization and the other one is memory allocation. The role of the new keyword is to create the object and the role of the constructor is to initialize the variables.

What are the rules to follow while working with C# Constructor?

• The constructor’s name should be the same as the class name.
• It should not contain a return type even void also.
• As part of the constructor body return statement with a value is not allowed.

What does a Constructor have in C#?

• It can have all five accessibility modifiers i.e. public, private, protected, etc.
• The constructor can be parameterless or parameterized.
• It can have a throws clause which means we can throw an exception from the constructor.
• The constructor can have logic, as part of logic it can have all C#.NET legal statements except return statements with value.
• We can place a return; in the constructor.

Can we define a method with the same class name in C#?

No, it is not allowed to define a method with the same class name in C#. It will give you a compile-time error. For a better understanding, please have a look at the below image.

In the next article, I am going to discuss the various Types of Constructors in C# with Examples. Here, in this article, I try to explain the basic concepts of Constructors in C# with Examples. I hope you enjoy this article. Please give your feedback, suggestions, and questions about this article in the comment section.

About the Author: Pranaya Rout

Pranaya Rout has published more than 3,000 articles in his 11-year career. Pranaya Rout has very good experience with Microsoft Technologies, Including C#, VB, ASP.NET MVC, ASP.NET Web API, EF, EF Core, ADO.NET, LINQ, SQL Server, MYSQL, Oracle, ASP.NET Core, Cloud Computing, Microservices, Design Patterns and still learning new technologies.

13 thoughts on “Constructors in C#”

this one is best site for acquire knowledge and for preparation of interview

yes you are right………………………

i have not understood below tow point

Can we initialize non-static data members within a static constructor in C#? It is not possible to initialize non-static data members within a static constructor, it raises a compilation error. Have a look at the following example.

static Example() { int = 101;//not allowed j = 100; } Can we initialize static data fields within a non-static constructor in C#? Yes, you can initialize static data members within a non-static constructor but after then they lose their static nature. Consider the following example:

public Example() { i = 100; j = 100; //allows but j lose its static nature

It’s good to provide execution order and base also…

Hi I think below line need to be correct “it is going to be invoked only once and that is during the creation of the first instance (object) of the class.”

My explanation: If we do not create any instance of the class, static constructor will be invoke when you run the application.

class Program { static Program() { Console.WriteLine(“test”); Console.ReadKey(); } static void Main(string[] args) { Console.WriteLine(“Hello World!”); } }

Output: test

I have one doubt you wrote like this

Rules to follow while creating the C# Constructors: ———–The constructor should not contain modifiers.

What a Constructor have in C#? ————It can have all five accessibility modifiers.

I did not get the point you wrote should not contain modifier and 5 modifer what it means

Sorry Please Ignore the above one

If the below point is not correct, please update your content, so that no any another person can read the same wrong statement.

Rules to follow while creating the C# Constructors: ———–The constructor should not contain modifiers.

yes constructor should not contain modifiers Modifier keywords are : abstract async const event extern new override partial readonly sealed static unsafe virtual volatile

Articles are great. I have a suggestion. You should use dark theme.

Very thoroughly explained

Super explanation….. a lot of thanks .you are great.

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C# Tutorial

C# examples, c# constructors, constructors.

A constructor is a special method that is used to initialize objects. The advantage of a constructor, is that it is called when an object of a class is created. It can be used to set initial values for fields:

Create a constructor:

Try it Yourself »

Note that the constructor name must match the class name , and it cannot have a return type (like void or int ).

Also note that the constructor is called when the object is created.

All classes have constructors by default: if you do not create a class constructor yourself, C# creates one for you. However, then you are not able to set initial values for fields.

Constructors save time! Take a look at the last example on this page to really understand why.

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Constructor Parameters

Constructors can also take parameters, which is used to initialize fields.

The following example adds a string modelName parameter to the constructor. Inside the constructor we set model to modelName ( model=modelName ). When we call the constructor, we pass a parameter to the constructor ( "Mustang" ), which will set the value of model to "Mustang" :

You can have as many parameters as you want:

Tip: Just like other methods, constructors can be overloaded by using different numbers of parameters.

Constructors Save Time

When you consider the example from the previous chapter, you will notice that constructors are very useful, as they help reducing the amount of code:

Instead of adding values to fields one by one, you can use a constructor that automatically runs when an object is created; which will set default values from the beginning.

Without constructor:

With constructor:

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How to Find the Latitude and Longitude of a Location in C#

Posted by Ellie Zubrowski | May 11, 2024 | 0

Want to build great APIs? Or become even better at it? Check our Ultimate ASP.NET Core Web API program and learn how to create a full production-ready ASP.NET Core API using only the latest .NET technologies. Bonus materials (Security book, Docker book, and other bonus files) are included in the Premium package!

In this article, we will learn how to find the latitude and longitude of a location in C# using the Google Maps Geocoding API. We’ll introduce two different methods for obtaining the coordinates: using the GoogleMaps.LocationServices NuGet package, which simplifies the process but can be less flexible, and using HttpClient directly, which provides us more control over HTTP requests and responses.

So, let’s begin.

Get an API Key and Configure the Project

First, to get the latitude and longitude of an address, we’ll need to get an API key from Google. To do this, we visit Google’s developer documentation for instructions on getting one. It’s also important to secure our API key to ensure no one else can use it . To accomplish this, we will store our API key using the Secret Manager tool to keep it safe.

Next, let’s define an address for our testing:

var address = "Miami, Florida";

Now, let’s create a simple console application and set up our ConfigurationBuilder :

This configuration builder helps us get the API key from the secret manager. Here, we initialize a ConfigurationBuilder , and then add user secrets to the Program class. We then call Build() to build our configuration. Our configuration object now has the settings from our user secrets.

Next, we retrieve the API key value from the configuration using the key "Secret:MyApiKey" (We can name this whatever we call our API key in the secret manager). Next, we verify that we have successfully loaded our API key (i.e. validate its existence), by ensuring it’s not null or empty.

Now, we can begin getting our coordinates!

Find the Latitude and Longitude of a Location via GoogleMaps.LocationServices NuGet Package

First, we install the GoogleMaps.LocationServices NuGet package:

dotnet add package GoogleMaps.LocationServices

The Google Maps Location Services package allows our app to communicate with Google Maps for location services, which includes getting the latitude and longitude.

We start by defining the model:

Here, we define a CustomMapPoint class. We will use this class to return a latitude and a longitude in our methods. The [Required] attribute ensures that Longitude and Latitude are provided to help us avoid situations where we have incomplete or incorrect location data.

Implementing the Service

Next, we create an interface that tells our app what a location service should do:

Here, the IMapLocationService interface allows us to use different mapping services if needed, not just Google Maps, without changing much of our code. Within our new interface, we define the method GetLatLongFromAddressAsync() , which takes an address as a parameter and asynchronously returns a CustomMapPoint object. 

Now, we wrap Google’s location service into a class that implements our interface:

Here, we declare our class GoogleLocationServiceWrapper which implements the IMapLocationService interface. Then, we declare a private readonly field _glsContext with the type GoogleLocationService . This field will hold an instance of Google’s location service that we’ll use to get the coordinates.

In the constructor, we initialize _glsContext with a new instance of GoogleLocationService passing an API key as a parameter. We do this to authenticate requests to Google’s location service.

We then implement the asynchronous method GetLatLongFromAddressAsync() from our interface. In the method, we use the _glsContext instance to call GetLatLongFromAddress() , passing in our address. We also wrap this call in Task.Run() , making it asynchronous and thus preventing it from blocking the main execution thread. This method then communicates with Google’s location service and returns a location object containing our latitude and longitude values.

Lastly, we create and return a new CustomMapPoint object, setting its Latitude and Longitude properties to the values from the location object.

Getting the Latitude and Longitude

After installing the Google Maps Location Services package, setting up the CustomMapPoint model,  IMapLocationService interface and creating a GoogleLocationServiceWrapper , we can now get our coordinates:

Here, we create the LatLongWithNuGet class. This class uses a private readonly field for the IMapLocationService , making sure that the service we provided to the class at the start doesn’t change later on.

Then, the class constructor takes an IMapLocationService as the type of parameter, allowing the class to work with any service that follows this interface.

Next, in the GetLatLongWithNuGet method, we try to get the coordinates of an address asynchronously. If the location service successfully finds the address, it returns the coordinates. If not, the catch block catches any errors and returns an error message.

Finally, in Program.cs , we can get the latitude and longitude:

First, we create locationService using GoogleLocationServiceWrapper and our API key, connecting us to Google’s location services. Then, we initialize a LatLongWithNuGet instance passing in our locationService object. Finally, we asynchronously retrieve our coordinates by calling the GetLatLongWithNuGet() method on the latLongWithNuGet instance:

Address (Miami, Florida) is at 25.7616798, -80.1917902

Even though we have the latitude and longitude, let’s try one other way of getting the coordinates using HttpClient directly. 

Find the Latitude and Longitude of a Location via HttpClient

Here, we’re using HttpClient to get the latitude and longitude of Miami, Florida by communicating with Google’s Geocoding API. One advantage of using HttpClient directly is that it offers more control and flexibility. Additionally, to better manage HttpClient , we will use the IHttpClientFactory interface.

Setting Up HttpClient for Geocoding

Since we are using IHttpClientFactory , we first add the Microsoft.Extensions.Http package: 

dotnet add package Microsoft.Extensions.Http

This package introduces IHttpClientFactory , which helps us better manage HttpClient instances in our projects. It’s a game-changer for creating and using HttpClient in a way that improves application performance and reliability.

We use IHttpClientFactory because directly instantiating HttpClient can lead to challenges like socket exhaustion and slow performance.

After we add the package, we can move on to create our LatLongWithHttpClient class:

Here, in our LatLongWithHttpClient class, we implement the IMapLocationService interface that we created previously. This is to make sure our code is compatible with different mapping services. This class includes private readonly fields _httpClientFactory and _apiKey . _httpClientFactory is used for creating instances of HttpClient for web requests to Google’s Geocoding API. Both fields are private and readonly because they are only needed within this class and shouldn’t change once we initialize them. We then initialize these fields in the constructor.

Creating Our Geocoding Method

Let’s move on to our GetLatLongWithAddressAsync  method:

Here, the GetLatLongWithAddressAsync  method uses async tasks to find the latitude and longitude using Google’s Geocoding API. We start by using _httpClientFactory.CreateClient("MapsClient") to get an instance of HttpClient that’s set up for mapping services. This instance is assigned to the httpClient variable. The "MapsClient" refers to the settings we define later in Program.cs , which will include the base URL for Google’s Geocoding API. 

After that, we initialize relativeUri with the address and API key.

Then, we send a GET request with httpClient.GetAsync(relativeUri) and wait for the response. After checking for a successful status with response.EnsureSuccessStatusCode() , we parse the JSON response and assign it to the variable root .

If the response status is “OK”, we go through root to get the latitude and longitude:

First, root.GetProperty("results")[0] allows us to access the first item in the “results” array.

Then, .GetProperty("geometry").GetProperty("location") reaches the “location” object, where the geographic data is found, and assigns the data to the location variable.

After that, we create and return a new CustomMapPoint object, setting its Latitude and Longitude properties using location.GetProperty("lat").GetDouble() and location.GetProperty("lng").GetDouble() . 

However, if the status isn’t “OK”, the method throws an exception.

Getting the Latitude and Longitude of a Location

Finally, in Program.cs , we can get our coordinates:

Here, we initialize a new ServiceCollection , which serves as a container for adding and configuring services. It’s where we register dependencies that our application will use.

Then, we register a named instance of HttpClient configured with a base address set to Google’s Geocoding API URL.

Next, we add LatLongWithHttpClient as a singleton service. This means that one instance of LatLongWithHttpClient will be created and used throughout the app’s lifetime. This instance is created using IHttpClientFactory and an apiKey , both fetched from the service collection. IHttpClientFactory is injected to help with the creation of HttpClient instances that are pre-configured with the settings defined earlier (like the base address). This simplifies how our app handles resources and keeps HTTP request settings consistent across the board.

After that, BuildServiceProvider turns the service collection into a service provider that can create and supply the registered services whenever needed.

Once that is set up, we use GetRequiredService<LatLongWithHttpClient>() to fetch the LatLongWithHttpClient instance from the service container. If it’s unavailable, it will throw an exception. 

Lastly, we use the latLongWithHttpClient instance to call GetLatLongFromAddressAsync() with an address. This asynchronous method gets the latitude and longitude of the address and assigns the result to coordinatesHttpClient . The latitude and longitude values are stored as properties of this object, specifically coordinatesHttpClient.Latitude and coordinatesHttpClient.Longitude .

After we run the code, we should see this in the console:

In this article, we covered two methods to find the latitude and longitude of a location in C#. We demonstrated using HttpClient through IHttpClientFactory for direct API calls, and using the GoogleMaps.LocationServices NuGet package.

Both methods interact with the Google Maps Geocoding API but offer different levels of control and simplicity.

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