What is C#?
C# (pronounced as C-Sharp) is an Object Oriented programming language developed by Microsoft. This language is very similar to Java and was developed to bring together C++ features and the easy programming of Visual Basic (VB).
Difference between C++ and C#?
C#
• C# is a higher level programming language built over C++ programming language.
• It is similar to Java.
• It can be considered as a hybrid programming language consisting of features of C++ and ease of use of VB.Net.
C++
• C++ is a low level programming language built by adding object oriented concepts to the C programming language.
• It is NOT similar to Java.
• C++ itself is a language and does not inherit any features of other languages.
What is Struct and Class in C#?
Struct
• Value Type i.e. whenever a variable is created, it holds the value.
• Copying a Struct variable, copies the value.
• A new variable is created in Stack memory.
• Cannot be inherited.
• Cannot be of Abstract type.
• Cannot contain Private parameterless constructors.
• Doesn’t support Destructor.
Class
• Reference Type i.e. whenever a variable is created, it holds the reference (address) while the value is stored some location.
• Copying a Class variable, copies the reference while the value remains on same location.
• A new variable is created in Heap memory.
• Can be inherited.
• Can be of Abstract type.
• Can contain Private parameterless constructors.
• Supports Destructor.
Difference between String and StringBuilder in C#?
String
• Belongs to the System namespace.
• Immutable i.e. whenever you append a String object it creates a new object with new memory allocation.
• When changed, a new object is created and old object is destroyed.
• Avoid using inside loops, as if the loop executes N times. N memory allocation operations will be performed.
• Concat function is used for String concatenation.
Example:
string s = "Mudassar";
s = string.Concat(s, "Khan");
StringBuilder
• Belongs to the System.Text namespace.
• Mutable i.e. whenever you append a String object it does not creates a new object with new memory allocation.
• When changed, no new object is created or old object is destroyed.
• Recommended for loops, as only the size of object will change.
• Append function is used for String concatenation.
Example:
StringBuilder sb = new StringBuilder();
sb.Append("Mudassar");
sb.Append("Khan");
What is Static function and example of in-built Static function in .Net?
• Has the keyword static.
• A Static function is one that can be accessed without creating an object of the class.
• It can be accessed using the name of the class.
• It can belong to Static as well as Non-Static classes.
• One cannot use external Non-Static objects and functions inside a Static method.
• One can use Static function in Static as well as Non-Static classes.
• Keyword this is not supported.
• Example of one inbuilt Static function in C# is Convert.ToString().
Example:
public class A
{
public static void C()
{
//Invalid
this.D();
}
public void D()
{
//Valid
C();
}
}
