What is StringBuilder in C#

The following article, What is StringBuilder in C# provides an outline for the StringBuilder in C#. Before talking about StringBuilder, lets first see the concept of immutability, if you are acquainted with the Strings then probably you would be knowing that strings have immutable nature i.e. each time a new object is created and new memory location is provided to it and hence whenever data change happens, the changed data is to be placed into a new memory location and keeping the original string safe. Now, let us pay little thought. What is the use case of this approach? Well, if you are setting credentials like database details, other credentials which won’t be changed in the transient time, then you can use String for that to keep them safe. Now there comes another kind of object, so-called StringBuilder, i.e. mutable in nature, hence saves memory for you by allowing you to modify data in the current memory location only. Such things come in handy when you are looking to have multiple append operations to come your way.

Definition of StringBuilder in C#

StringBuilder is a class that represents a mutable set of characters and it is an object of the System. Text namespace. StringBuilder is a dynamic object in nature and hence StringBuilder doesn’t create a new object in the memory, rather it dynamically expands the required memory to incorporate the modified or new string. String builders don’t appear convincing in a multithreading environment as they can result in data inconsistency when written over by multiple threads if the multithreading concept is not used properly.

Understanding StringBuilder

1. Now the point comes where one shall understand the results mutability can lead to, you should choose to use mutability only if the same set of data is going to expand dynamically, Let’s take an example to understand this scenario.

2. If you are taking some data from an HTML form which is to be stored into a table based on some business logic, which will first validate data, in that case, you can create a StringBuilder object and append all the data fields, in association with the columns of database and finally can execute an insert query to place that all in database, the advantage of such approach is that all the time new memory location was not supposed to be allocated. And C# will be managing that one memory location with dynamic expansion for you.

3. You can also specify the number capacity of StringBuilder in C#.

StringBuilder s=new StringBuilder(10);

StringBuilder s=new StringBuilder("object value", 15);

4. The StringBuilder.length property indicates the number of characters the StringBuilder object currently contains. If you add characters to the StringBuilder object, its length increases until it equals the size of the StringBuilder.

How does StringBuilder in C# make working so easy?

There are certain methods provided in C#, which makes working with StringBuilder easy. StringBuilder class provides the following methods to make the developer’s task easy –

• Append( String val ) – is used to append a string value of an object to the end of the current StringBuilder object.

Example –

classStringBuilder a = new StringBuilder("val",10);
a.append("us")

when you do console.writeline(a), it will give you result “value”

• Append( Format ) – is used to format the input string into the specified format and thereafter append it.

Example –

StringBuilder a = new StringBuilder("val",10);
a.appendFormat("{0:C}",10)

Kindly execute this and analyze the variation from what has been done in the simple append() method.

• Insert( int index, string value ) – inserts the string at the specified index in StringBuilder object.

Example

StringBuilder a = new StringBuilder("val",10); a.insert(4,"ue")

Execute and see the result

• There are other methods also, and many variants of the above-mentioned methods, for those please refer to this link

What can you do with StringBuilder?

• StringBuilder has many properties, methods and constructors to take care of coding problems like we saw StringBuilder() constructor, there are variants like StringBuilder( String, Int32, Int32, Int32 ) – this will initialize a new instance of the StringBuilder class from the mentioned substring and its capacity.
• There are properties like – length, capacity, max capacity.
• There are methods like – appendLine(), Equals( object ), GetHashCode(), GetType(), Remove( int32, int32 ), Replace( char,char ), toString().

These all make a task for coding typical business problems easily and with fewer lines of code.

Working with StringBuilder in C#?

• Instantiation of the StringBuilder object by calling the StringBuilder ( Int32, Int32 ) constructor can make the length and the capacity of the StringBuilder instance to grow beyond MaxCapacity property value. Primarily this could happen when you call the Append ( String ) and AppendFormat ( String, Object ) methods to append small strings.
• If the number of added characters causes the length of the StringBuilder object to exceed its current capacity, new memory is allocated, the value of the Capacity property is doubled, new characters are added to the StringBuilder object, and its Length property is adjusted.
• Once the maximum capacity is reached, any further memory allocation is not possible for the StringBuilder object, and if in any case expansion beyond its maximum capacity is done then likely it throws any of the two errors mentioned.

ArgumentOutOfRangeException.
OutOfMemoryException.

Advantages

• No multiple memory locations to be taken care of by C#.
• Dynamic object expansion until the capacity.
• It can be converted to String and vice versa.

Why should we use StringBuilder in C#?

• It is seen that string follows the concat operations and StringBuilder follows the append operation and append
• appears to be faster than concat as concat has to allocate new memory location that has not to be done by StringBuilder.
• If the data is transient i.e. non-permanent and will vary among different calls then StringBuilder can be used, provided you are working with no multithreading, else thread-safety will be an issue.

Why do we need StringBuilder in C#?

Well, we have discussed this in the above points only and one can infer here the use cases where this can come in handy.

Conclusion

Hence we saw the difference between string and StringBuilder, when to use what and what are the challenges or exceptions that can appear while working with the StringBuilder.

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