Else–if ladder in Go - Mini Project: Build & Apply

Else-if ladder

📖 Scenario: You are building a simple program to categorize a person's age group based on their age. This is like sorting people into groups such as child, teenager, adult, or senior.

🎯 Goal: Create a Go program that uses an else-if ladder to check a person's age and print the correct age group.

📋 What You'll Learn

Create an integer variable called age with the value 25

Create a string variable called ageGroup to store the age category

Use an else-if ladder with if, else if, and else to assign the correct age group to ageGroup

Print the value of ageGroup

💡 Why This Matters

🌍 Real World

Age group categorization is common in apps that provide age-specific content or services, like games, health apps, or social platforms.

💼 Career

Understanding else-if ladders helps in decision-making logic, which is essential for software development, data processing, and user input validation.

1

DATA SETUP: Create the age variable

Create an integer variable called age and set it to 25.

Go

var age int = 25
// Your code here

Hint

Use var age int = 25 to create the variable.

2

CONFIGURATION: Create the ageGroup variable

Create a string variable called ageGroup and set it to an empty string "".

Go

package main

import "fmt"

func main() {
    var age int = 25
    var ageGroup string = ""
    // Your code here
}

Hint

Use var ageGroup string = "" to create the variable.

3

CORE LOGIC: Use an else-if ladder to assign ageGroup

Use an else-if ladder with if, else if, and else to assign ageGroup as follows: if age < 13, set ageGroup = "Child"; else if age < 20, set ageGroup = "Teenager"; else if age < 60, set ageGroup = "Adult"; else set ageGroup = "Senior".

Go

package main

import "fmt"

func main() {
    var age int = 25
    var ageGroup string = ""

    // Your code here
}

Hint

Use if, else if, and else blocks to check the age ranges and assign ageGroup.

4

OUTPUT: Print the ageGroup

Write a fmt.Println statement to print the value of ageGroup.

Go

package main

import "fmt"

func main() {
    var age int = 25
    var ageGroup string = ""

    if age < 13 {
        ageGroup = "Child"
    } else if age < 20 {
        ageGroup = "Teenager"
    } else if age < 60 {
        ageGroup = "Adult"
    } else {
        ageGroup = "Senior"
    }

    // Your code here
}

Hint

Use fmt.Println(ageGroup) to print the age group.

Practice

1. What does an else-if ladder do in Go programming?

easy

A. Checks multiple conditions one by one and runs the first true block

B. Runs all conditions regardless of their truth value

C. Only runs the last condition in the ladder

D. Skips all conditions and runs default code always

Solution

1. Step 1: Understand else-if ladder behavior

   An else-if ladder checks conditions in order, from top to bottom.

2. Step 2: Identify which block runs

   Only the first condition that is true will run its code block; others are skipped.

3. Final Answer:

   Checks multiple conditions one by one and runs the first true block -> Option A

4. Quick Check:

   Else-if ladder = first true block runs [OK]

Hint: Remember: else-if stops at first true condition [OK]

Common Mistakes:

• Thinking all conditions run even if one is true
• Believing else-if runs only the last condition
• Confusing else-if with separate if statements

2. Which of the following is the correct syntax for an else-if ladder in Go?

easy

A. if condition1 { } else if condition2 { } else { }

B. if condition1 { } elseif condition2 { } else { }

C. if condition1 { } else if(condition2) { } else { }

D. if condition1 then { } else if condition2 { } else { }

Solution

1. Step 1: Recall Go else-if syntax

   Go uses else if as two separate words without parentheses around the condition.

2. Step 2: Compare options

   if condition1 { } else if condition2 { } else { } matches Go syntax exactly; others use wrong keywords or parentheses.

3. Final Answer:

   if condition1 { } else if condition2 { } else { } -> Option A

4. Quick Check:

   Go else-if = "else if" two words, no parentheses [OK]

Hint: Use 'else if' with space, no parentheses in Go [OK]

Common Mistakes:

• Writing 'elseif' as one word
• Adding parentheses around else-if condition
• Using 'then' keyword

3. What will be the output of this Go code?

package main
import "fmt"
func main() {
  x := 15
  if x < 10 {
    fmt.Println("Less than 10")
  } else if x < 20 {
    fmt.Println("Less than 20")
  } else {
    fmt.Println("20 or more")
  }
}

medium

A. Less than 10

B. Less than 20

C. 20 or more

D. No output

Solution

1. Step 1: Check first condition (x < 10)

   x is 15, which is not less than 10, so skip this block.

2. Step 2: Check second condition (x < 20)

   15 is less than 20, so this block runs and prints "Less than 20".

3. Final Answer:

   Less than 20 -> Option B

4. Quick Check:

   15 < 20 = true, prints "Less than 20" [OK]

Hint: Check conditions top to bottom, first true runs [OK]

Common Mistakes:

• Choosing first condition without checking value
• Ignoring else-if and picking else block
• Assuming all blocks print

4. Find the error in this Go else-if ladder code:

if score >= 90 {
  fmt.Println("A")
} else if score >= 80
  fmt.Println("B")
} else {
  fmt.Println("C")
}

medium

A. else block should come before else if

B. Wrong comparison operator used

C. Missing braces {} after else if condition

D. No error, code is correct

Solution

1. Step 1: Check else-if syntax

   In Go, the else-if condition must be followed by braces {} enclosing the code block.

2. Step 2: Identify missing braces

   The else-if block lacks opening brace after condition, causing syntax error.

3. Final Answer:

   Missing braces {} after else if condition -> Option C

4. Quick Check:

   Braces required after else-if condition [OK]

Hint: Always use braces {} after if and else-if conditions [OK]

Common Mistakes:

• Omitting braces after else-if condition
• Placing else before else-if
• Using wrong operators

5. You want to write a Go program that prints "Child" if age < 13, "Teen" if age is between 13 and 19 inclusive, "Adult" if age is 20 or more. Which else-if ladder correctly implements this?

hard

A. if age <= 13 {
fmt.Println("Child")
} else if age >= 13 && age <= 19 {
fmt.Println("Teen")
} else {
fmt.Println("Adult")
}

B. if age <= 13 {
fmt.Println("Child")
} else if age > 13 && age < 19 {
fmt.Println("Teen")
} else {
fmt.Println("Adult")
}

C. if age < 13 {
fmt.Println("Child")
} else if age > 13 && age < 19 {
fmt.Println("Teen")
} else {
fmt.Println("Adult")
}

D. if age < 13 {
fmt.Println("Child")
} else if age >= 13 && age <= 19 {
fmt.Println("Teen")
} else {
fmt.Println("Adult")
}

Solution

1. Step 1: Check child condition

   Child is age less than 13, so condition is age < 13.

2. Step 2: Check teen condition

   Teen is age between 13 and 19 inclusive, so condition is age >= 13 && age <= 19.

3. Step 3: Check adult condition

   Adult is age 20 or more, so else block covers this.

4. Final Answer:

   if age < 13 { ... } else if age >= 13 && age <= 19 { ... } else { ... } -> Option D

5. Quick Check:

   Conditions match age groups exactly [OK]

Hint: Use inclusive ranges carefully with >= and <= [OK]

Common Mistakes:

• Using wrong comparison operators for ranges
• Overlapping or missing age values
• Incorrect else-if order