Conditional Statements Concepts

Conditional expressions and conditional costructs are features of a programming language which perform different computations or actions depending on whether a programmer-specified boolean condition evaluates to true or false.

There are some principles, These are:

If Statements
If / Else Statements
Switch Statements

If Statements

An If Statement is a conditional statement in which it executes a block of code if a specified condition is true.

An Example of how an If Statement works in JavaScript - Here is the given code:


							var myNum = 2;

if(myNum == 2){
	
	console.log("it is true");

}

// Output:

// it is true

The if statement above checks if the condition is true (myNum being equivalent to 2). If it is true, which it is, then "is it true" is printed.

As exaplained above, the If statement is quite easy to grasp, they can also be put into loops to make dynamic algorithms and efficient codes.

If / Else Statements

Else statements are useful as an opposite to the if statement. If the condition is false, then another block of code can be executed. The Else statement has to always follow the If statement.

An Example of how Else statements work in Java - Here is the given code:


							int myVar = 2;

if(myVar == 3){
	
	System.out.println("hi");

} else {
	
	System.out.println("this is false");

}

// output:

// this is false

The If statement is executed first, and then the else statement is executed next, but what if we want to add another specific condition without adding a separate IF statement. Welcome to the Else IF statement!


							int myVar = 2;

if(myVar == 3){
	
	System.out.println("hi");

} else if (myVar == 1){
	
	System.out.println("hi again");

} else {
	
	System.out.println("this is false");

}

// output:

// this is false

The Else If statement allows for multiple If statements if the first If statement is false.

This again, coupled with for/while loops in functions helps to make dynamic algorithms.

Switch Statements

A Switch statement is a statement in which you have multiple If statements, and there is a variable which can access all each outcome.

An Example of how Switch statements work in JavaScript - Here is the given code:


							var day = 5;
var dayName = "";

switch (day){
	
	case 0:
		dayName = "Sunday";
		break;
	case 1:
		dayName = "Monday";
		break;
	case 2:
		dayName = "Tuesday";
		break;
	case 3:
		dayName = "Wednesday";
		break;
	case 4:
		dayName = "Thursday";
		break;
	case 5:
		dayName = "Friday";
		break;
	case 6:
		dayName = "Saturday";
		break;

}

console.log(dayName);

// output:

// "Friday"

The Switch statement checks the cases for the variable "day", and since day is equal to 5, case 5 is valid and so the output is "Friday". The below statement uses the "default" keyword.


							var day = 4;
var dayName = "";
switch (day){
	
	case 0:
		dayName = "Weekend";
		break;
	case 6:
		dayName = "Weekend";
		break;
	default:
		dayName = "Not Weekend";

}

console.log(dayName);

// output:

// "Not Weekend"

The "Default" keyword writes a message as a default for the Switch statement if the statement does not match any cases.

Switch statements are important for multiple outcomes, they are useful, but are usually really slow compared to other if/else statements. It is good practice include a default keyword in a Switch statement.

These are the concepts of conditional statements.