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An if statement can be followed by an optional else if…else statement, which is very useful to test various conditions using a single if…else if statement. Or we can say that if… else if…else statements allow you to check multiple conditions sequentially.
It creates a decision tree where each condition is evaluated in an order and the first true condition’s block of statement will execute. If no condition is true, then the else part will execute. If…else if…else statements are also known as if… else ladder.
When using if, else if, and else statements, there are a few points to keep in mind.
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An if can have zero or one else”s and it must come after any else if”s.
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An if can have zero to many else if”s and they must come before the else.
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Once an else if succeeds, none of the remaining else if”s or else”s will be tested.
Syntax
Following is the syntax of the if…else if…else statement −
if boolean_expression1{ /* Execute when the boolean expression 1 is true */ } else if boolean_expression2{ /*Execute when the boolean expression 2 is true*/ } else if boolean_expression3{ /*Execute when the boolean expression 3 is true*/ }else{ /* Execure when none of the above conditions is true */ }
Flow Diagram
The following flow diagram will show how if…else if…else statement works.
Example
Swift program to demonstrate the use of if… else if…else statement.
import Foundation var varA:Int = 100; /* Check the boolean condition using the if statement */ if varA == 20 { /* If the condition is true then print the following */ print("varA is equal to than 20"); } else if varA == 50 { /* If the condition is true then print the following */ print("varA is equal to than 50"); } else { /* If the condition is false then print the following */ print("None of the values is matching"); } print("Value of variable varA is (varA)");
Output
It will produce the following output −
None of the values is matching Value of variable varA is 100
Example
Swift program to check the current season using if…else ladder.
import Foundation let myMonth = 5 // Checking Season using if...else ladder if myMonth >= 3 && myMonth <= 5 { print("Current Season is Spring") } else if myMonth >= 6 && myMonth <= 8 { print("Current Season is Summer") } else if myMonth >= 9 && myMonth <= 11 { print("Current Season is Autumn") } else { print("Current Season is Winter") }
Output
It will produce the following output −
Current Season is Spring
Example
Swift program to calculate the grade of the student using if…else if…else statement.
import Foundation let marks = 89 // Determine the grade of the student if marks >= 90 { print("Grade A") } else if marks >= 80 { print("Grade B") } else if marks >= 70 { print("Grade C") } else if marks >= 60 { print("Grade D") } else { print("Grade F") }
Output
It will produce the following output −
Grade B
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