# Else if statement or Nested if-else statement in R:

Multiple conditions can be tested in a single code using the nested if-else statement. The important considerations are:

• There can be either no “else” statement or one “else” statement associated with an “if “statement.
• The “else” statement must come after any “else if” statement.
• “if” statements can have many “else if” statements.
• The “else if” statements come before the “else” statement.
• The “else if” statements or “else” statement is tested only till one of the “else if” statement succeeds.

### Syntax:

if(boolean_expression 1) { // Execute this code if this condition is true. } else if( boolean_expression 2) { // Execute this code if this condition is true. } else if( boolean_expression 3) { // Execute this code if this condition is true. } else { // Execute this code if all the conditions are false }

### Example 1:

x <- 1000 y <- 800   if (y > x) { print("y is greater than x") } else if (x == y) { print("x and y are equal") } else { print("x is greater than y") }

Output:

[1] "x is greater than y"

### Example 2:

age <- 20 if(age<18) { print("Not Eligible") }else if(age>30){ print("Not Eligible") }else { print("Eligible") }

Output:

[1] "Eligible"

### Example 3:

Percentage = 55; if(Percentage>70){ print("First Rank") }else if(Percentage>60){ print("Second Rank") }else if(Percentage>50){ print("Third Rank") }else{ print("Fail") }

Output:

[1] "Third Rank"

### Example 4:

cat("Choice 1: SUM = 200+300 \n") cat("Choice 2: SUBTRACTION = 200-300 \n") cat("Choice 3: PRODUCT = 200*300 \n") cat("Choice 4: DIVISION = 200/300 \n") x <- 200 y <- 300 choice <- 2 if(choice==1){ sum <-(x+y) cat("\nSUM =",sum) }else if(choice==2){ sub<-(x-y) cat("\nSUBTRACTION =",sub) }else if(choice==3){ mul<-x*y cat("\nPRODUCT =",mul) }else if(choice==4){ div<-x/y cat("\nDIVISION =",div) }else{ cat("Wrong Option!!") }

Output:

Choice 1: SUM = 200+300 Choice 2: SUBTRACTION = 200-300 Choice 3: PRODUCT = 200*300 Choice 4: DIVISION = 200/300   SUBTRACTION = -100

### Example 5:

num1 = 9 num2 = 88 num3 = 303 num4 = 555 num5 = 201 if(num1>num2){ if(num1>num3 && num1>num4 && num1>num5){ max_num = num1 } }else if(num2>num3){ if(num2>num1 && num2>num4 && num2>num5){ max_num = num2 } }else if(num3>num4){ if(num3>num1 && num3>num2 && num3>num5){ max_num = num3 } }else if(num4>num5){ if(num4>num1 && num4>num2 && num4>num3){ max_num = num4 } }else{ max_num = num5 } cat("The largest number among 9, 88, 303, 555, 201 = ",max_num)

Output:

The largest number among 9, 88, 303, 555, 201 = 555