Else–if ladder in Go - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is an else-if ladder in Go?

An else-if ladder is a way to check multiple conditions one after another. It uses if, else if, and else blocks to decide which code to run based on conditions.

beginner

How do you write an else-if ladder in Go?

You start with an if statement, then add one or more else if statements, and optionally end with an else statement. Each checks a condition in order.

beginner

What happens if none of the conditions in an else-if ladder are true?

If none of the if or else if conditions are true, the code inside the else block runs. If there is no else block, nothing happens.

beginner

Can you have multiple else if blocks in a Go else-if ladder?

Yes, you can have as many else if blocks as you want. Go checks each condition in order until one is true.

beginner

Write a simple else-if ladder in Go that prints "small", "medium", or "large" based on a number variable.

Example: var size int = 10 if size < 5 { fmt.Println("small") } else if size < 15 { fmt.Println("medium") } else { fmt.Println("large") }

In Go, what keyword starts an else-if ladder?

A if

B else

C elseif

D elif

The else-if ladder always starts with an if statement in Go.

What happens if multiple else-if conditions are true in Go?

A All true blocks run

B None run

C The last true block runs

D Only the first true block runs

Go runs only the first block whose condition is true in an else-if ladder.

Which of these is the correct else-if syntax in Go?

A else if condition { }

B elseif condition { }

C elif condition { }

D else(condition) { }

Go uses 'else if' with a space, not 'elseif' or 'elif'.

Is the else block mandatory in an else-if ladder in Go?

A Only if there are multiple else ifs

B Yes, always required

C No, it is optional

D Only if the first if is false

The else block is optional; you can have just if and else if blocks.

What will this code print if x = 20? if x < 10 { fmt.Println("Low") } else if x < 30 { fmt.Println("Medium") } else { fmt.Println("High") }

A Low

B Medium

C High

D Nothing

Since 20 is less than 30 but not less than 10, the else if block runs and prints "Medium".

Explain how an else-if ladder works in Go and why it is useful.

Think about checking different cases one by one.

Write a Go program snippet using an else-if ladder to categorize an integer score into grades: A, B, C, or F.

Use if, else if, and else blocks with comparison operators.

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