String VS StringBuilder class in Asp.Net C#

String and StringBuilder class are used to handle the strings but there are many differences between these two, regarding their use and namespace to which they belong.

In this article I will explain the difference between String and StringBuilder class in ASP.NET with C# and When to use String and when to use StringBuilder and why?

1.     Performance :

Performance of string builder is high as compared to string.

Consider the following concatenation example:

String str= "";
str += "Say ";
str += " Hello ";
str += "To World";

Output string will be Say Hello To World.

Let's do the same concatenation operation using StringBuilder class

StringBuilder sb = new StringBuilder("");
sb.Append("Say ");
sb.Append("Hello ");
sb.Append("To World ");
String str = sb.ToString();

Output string will be Say hello To World.

Output is same in both the cases. Then how can we measure the performance difference?

 Whenever we concatenate new string to the old string then String class always create new object of string type in memory whereas in case of string builder class, does not create new space in memory and update the same string.

So it is clear string builder consume less space than string. So it is recommended to use string builder to manipulate string.

2)  String Concatenation can be done using '+' operator or using the String.Concat method whereas in case of StringBuilder we use Append() method to concatenate.

3) String is Immutable (Non Modifiable) whereas StringBuilder is a Mutable Class

String is immutable: Every time we concatenate new string to old, string class create new object of string type. So it cannot be modify.

StringBuilder is mutable. It means in case of string builder class, does not create new space in memory and update the same string.

4) String class comes under namespace System while StringBuilder class belongs to the namespaceSystem.Text.

5) When string concatenation takes place, additional memory will be allocated whereas in case of StringBuffer additional memory will be allocated only when the string buffer capacity exceeds.

When to use String or StringBuilder Class?

If string manipulation is small then we should use string class, extra memory is affordable in that case. But for large string manipulations it is recommended to use StringBuilder class, because it uses less space than string.