One of the ways that C# makes it easier to develop network programs is the manipulation of strings. As we will see later, much of the effort in socket programming is string manipulation. It is amazing how many security holes start with simple buffer overflows. C# handles strings in two different ways and you are going to want to get to know them.

Look at this code snippet and think about what is going on.

String astring = new string(“hello”);
astring+= “ “;
astring +=”world”;
Console.WriteLine(“My string = ‘{0}’”, astring);

Instantiate a string and then append it twice right? Logically this is true but .NET actually does not do it that way. When you create a string a set amount of memory is allocated and that allocation cannot be changed. This means that strings are immutable. So when you modify a string C# creates a new memory space for it and flags the original one for the next cycle of garbage collection. The creation of a new memory space, placing the new value in it, and pointing to it creates overhead. Garbage collection is only a partial solution. The original memory is not reclaimed until the garbage collector gets around to it. Now look at the example above. The process of creating the new string and abandoning the old one actually happens twice, leaving 3 separate strings allocated in memory.

Instead you should use the StringBuilder class which is in the System.Text namespace. This saves resources because the StringBuilder class paradoxically does not create strings, it creates StringBuilder objects. An instance of the StringBuilder class starts with a minimum of 16 bytes of memory and dynamically can increase of decrease this memory utilization. You can use the Length property of the StringBuilder object to manually change the memory allocated.

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