Difference between String and String Builder in c#.

String

String is immutable. Immutable means once we create string object we cannot modify. Any operation like insert, replace or append happened to change string simply it will discard the old value and it will create new instance in memory to hold the new value.

string str = "hi"; // create a new string instance instead of changing the old one str += "test"; str += "help";

 

String Builder

String builder is mutable it means once we create string builder object we can perform any operation like insert, replace or append without creating new instance for every time.

StringBuilder sb = new StringBuilder(""); sb.Append("hi"); sb.Append("test "); string str = sb.ToString();

Example:

class Program { static void Main(string[] args) { //for example:  string str = "hello"; //Creates a new object when we concatenate any other words along with str variable it does not actually modify the str variable, instead it creates a whole new string.  str = str + " to all"; Console.WriteLine(str); StringBuilder s = new StringBuilder("Hi"); s.Append(" To All"); Console.WriteLine(s); Console.Read(); } }

Differences

String	String Builder
It’s an immutable	It’s mutable
Performance wise string is slow because every time it will create new instance	Performance wise string builder is high because it will use same instance of object to perform any action
In string we don’t have append keyword	In String Builder we can use append keyword
String belongs to System namespace	String builder belongs to System. Text namespace