Skip to main content

String vs StringBuilder

Take a look at the code given below

string str = string.empty;

for(int i= 0 ; I < 100; i++)

{

str += i.ToString();

}

You should never use string concatenation inside a loop, the reason for this being that strings in java and c# are Immutable.What this mean is that each time you concatenate a string, a whole new string object is created with the older value appended to the concatenated value, ok what happens to the older string object ?? well it is left for the garbage collector.

So we got two points here

1) object creation means processing power and memory usage 2) in this example the garbage collector needs to clean up nearly 100 string objects !!!

So what’s the solution ??

Use StringBuilder class (C# - found in the System.Text anmespace), StringBuilder (java not sure of the namespace).

What StringBuilder class does is it actually appends, without actually creating a string object on concatenating , therefore u will be using only one StringBuilder instance in this example, which basically means less processing power and memory usage when instantiationg the StringBuilder instance and garbage collector need to clean only one object !!

Revise code

StringBuilder builder = new StringBuilder(100);

for(int i= 0 ; I < 100; i++)

{

builder.Append( i);

// Use builder.toString() to get the whole string back

}

But , don’t over use StringBuilders as well, for an example, don’t use StringBuilders when u try to concatenate 2 strings, this degrades performance

StringBuilder class has methods that can be used to optimize the string concatenations, for an example a stringBuilder object can be created using a specified string length to store like StringBuilder builder = new StringBuilder(100)

Any question on this or If u want to know how StringBuilders work internally ??, please send me a reply.

Comments

  1. A nice one...

    Seems you are having a nice time in your new project.

    BTW it's really better to set the initial size for the StringBuilder at the time you create it. If you look at the IL you'll find that if not specified, as I can recall, the initial size is default to 16. So, when ever you append more items & when it exceeds the default size - it has to call a seperate function to increase it's size - and this is a performance hit.

    ReplyDelete
  2. Thanx, Prabth, your are correct, keep sending u'r expertise, it helps me a lot has a starter!!!.
    I also found out that it's better you use the Append(int) method(I had wrriten the code has Append(i.ToString()), Where i is an Integer), The reason is that overloads make way to correctly convert the valus passed using the current Cultute info, More on this...

    ReplyDelete

Post a Comment

Popular posts from this blog

Hosting WCF services on IIS or Windows Services?

There came one of those questions from the client whether to use II7 hosting or windows service hosting for WCF services. I tried recollecting a few points and thought of writing it down.
WCF applications can be hosted in 2 main ways- In a Windows service- On IIS 7 and aboveWhen WCF was first released, IIS 6 did not support hosting WCF applications that support Non-HTTP communication like Net.TCP or Net.MSMQ and developers had to rely on hosting these services on Windows Services.With the release of IIS 7, it was possible to deploy these Non-Http based applications also on IIS 7. Following are the benefits of using IIS 7 to host WCF applications
Less development effort
Hosting on Windows service, mandates the creating of a Windows service installer project on windows service and writing code to instantiate the service, whereas the service could just be hosted on IIS by creating an application on IIS, no further development is needed, just the service implementation is n…

Task based Asynchronous pattern, Async & Await and .NET 4.5

One of the key features in .Net 4.5 is to write asynchronous programs much easier. So if I was to write asynchronous programs in .Net 2.0/3.5, I would either follow the event based model or the callback based model. For an example, a synchronous method that does intensive work (say the DoWork()) can be made asynchronous by using the following patterns
1) Implementing the IAsyncResult pattern. in this implementation, 2 methods are exposed for the DoWork() synchronous method, the BeginDoWork() and the EndDoWork() method. The user will call the BeingDoWork() passing in the required parameters and a callback of the delegate type AsyncCallback(IAsyncResult). The BeginDoWork() will spawn a new thread a return control back to the user. Once work is completed in the spawned method, as a last step, it will call the inform the AsyncResult implementation, which in turns will call the EndDoWork() (which is the callback that was passed in to the BeginDoWork()).
2) Implementing the event pattern. Her…

MEF (Managed Extensibility Framework), .NET 4, Dependency Injection and Plug-in Development

Almost after .Net 4 was released I remember reading about MEF (Managed Extensibility Framework), this was a framework for developers to compose their application with required dependencies. At first this looks like the Unity Container used for dependency injection, but MEF is much more than a dependency container but there is nothing stopping you from using MEF as a dependency injector.I remember around 5 years back when I was in a project that created a framework that allows developers to plug-in there modules as WinForm screens. The developer would create a set of screens with the intended functionalities and the drop this component in the bin folder of the framework and then will move on to do some painful configurations for the framework to pick up the module. Dropping the component into the bin folder and doing a bit of configuration is all that s needed for the framework to pick up display the screens. Typically, the configurations would also contain metadata about the screen.Al…