Switch statement

Switch statement is a multiway branch statement. It provides an efficient way to transfer the execution to different parts of a code based on the value of the expression. The switch expression is of type int, char, byte, or short, or of an enumeration type, or of string type. The expression is checked for different cases and the one match is executed.

Syntax
switch (expression) {
            case value1:
                  code1;
                  break;

            case value2:
                  code2;
                  break;
            .
            .
            .
            case valueN:
                  codeN;
                  break;

            default:
                  DefaultCode;
                  break;
}


Before entering coding part of switch statement, we'll study 3rd type of operator called Logical Operator.

3. Logical Operator
Logical Operators are useful to perform the logical operation between two operands like AND, OR, and NOT based on our requirements. Logical AND and Logical OR can only be used between 2 conditions.
Logical AND(&&) - If both Conditions are TRUE, it returns TRUE.
Logical OR(||) - If either one condition is TRUE, it returns TRUE.
Logical NOT(!) - If a condition is TRUE, it returns FALSE. If a condition is FALSE, it returns TRUE.


CODE

EG 1 . Get Username and Password from user, Create simple Login console application

static void Main(string[] args) {
    //Getting Username
    Console.Write("Enter Username : ");
    string username = Console.ReadLine();
    //Getting Password
    Console.Write("Enter Password : ");
    string password = Console.ReadLine();

    //Here we used Logical AND(&&), so both LHS and RHS condition need to True in order to make entire condition True
    switch (username == "info@coderscapsule.com" && password =="123456789") {
        case true:
        Console.WriteLine("You have unlocked your Phone!!!");
        break;
        case false:
        Console.WriteLine("Invalid Username/Password");
        break;
    }
}

CODE EXPLANATION
In the above code, we are getting username and password from user and we are checking whether username is info@coderscapsule.com and password is 123456789. Just because we used Logical AND(&&) operator between username and password, both username and password need to be true in order to make entire condition true. If we are getting username and password from user, there could be only 4 possible scenerios. We'll see each and every scenario in detail

SCENARIO 1 : Assume user going to enter both username and password Correct. Now both condition will turn True. TRUE && TRUE = TRUE. Now system will enter inside switch statement and look for case true. we already defined case true. System will enter inside that case and print out "You have unlocked your Phone!!!" in console. Then system will execute break keyword which is to terminate switch statement.

SCENARIO 2 : Assume user going to enter correct username and wrong password. TRUE && FALSE = FALSE. Now system will enter inside switch statement and look for case false. we already defined case false. System will enter inside that case and print out "Invalid Username/Password" in console. Then system will execute break keyword which is to terminate switch statement.

SCENARIO 3 : Assume user going to enter wrong username and correct password. FALSE && TRUE = FALSE. Now system will enter inside switch statement and look for case false. we already defined case false. System will enter inside that case and print out "Invalid Username/Password" in console. Then system will execute break keyword which is to terminate switch statement.

SCENARIO 4 : Assume user going to enter both username and password wrong. FALSE && FALSE = FALSE. Now system will enter inside switch statement and look for case false. we already defined case false. System will enter inside that case and print out "Invalid Username/Password" in console. Then system will execute break keyword which is to terminate switch statement.


TIP:
While writing switch statement only focus inside ( ) which is present after switch keyword. Inside that ( ) if system is going to return true or false write the condition for case true and case false. if its going to return any value write the value cases accordingly.


KEY NOTE
We can create switch statement inside switch statement. The concept of creating one switch statement inside another is known as Nested switch Statement. Not only we can create if inside if, switch inside switch we can also create if statement inside switch statement , switch statement inside if statement.

Exercises
1. Write a program to read any day(1 to 7) number in integer and display day name in the word using switch statement.
2. Write a profram to check whether a number is even or odd using switch statement.


(Click Here, For more exercises)