If–else statement in Go

Introduction

An if-else statement helps your program make choices. It runs different code depending on a condition.

To check if a user is old enough to access a website.

To decide if a number is positive or negative.

To choose what message to show based on the time of day.

To handle errors by checking if something went wrong.

To run different code when a button is clicked or not.

Syntax

Go

if condition {
    // code to run if condition is true
} else {
    // code to run if condition is false
}

The condition must be a statement that results in true or false.

Curly braces { } are required even for one line of code inside if or else.

Examples

This checks if age is 18 or more, then prints a message accordingly.

Go

if age >= 18 {
    fmt.Println("You are an adult.")
} else {
    fmt.Println("You are a minor.")
}

Prints "Passed" if score is above 50, otherwise "Failed".

Go

if score > 50 {
    fmt.Println("Passed")
} else {
    fmt.Println("Failed")
}

Sample Program

This program checks the temperature and prints if it is hot or cool.

Go

package main

import "fmt"

func main() {
    temperature := 30
    if temperature > 25 {
        fmt.Println("It's hot outside.")
    } else {
        fmt.Println("It's cool outside.")
    }
}

Important Notes

You can add more conditions using else if for multiple choices.

Always use curly braces to avoid mistakes, even if the block has one line.

Summary

If-else lets your program choose between two paths.

Use it when you want to run code only if a condition is true or false.

Remember to write conditions that result in true or false.

Practice

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

easy

A. It repeats code multiple times.

B. It declares a variable.

C. It defines a new function.

D. It chooses between two paths based on a condition.

Solution

1. Step 1: Understand the purpose of if-else

   An if-else statement checks a condition and runs code based on whether it is true or false.

2. Step 2: Compare with other options

   Repeating code is done by loops, functions define reusable code, and variables store data, so these are not correct.

3. Final Answer:

   It chooses between two paths based on a condition. -> Option D

4. Quick Check:

   If-else = choose path [OK]

Hint: If-else picks true or false path fast [OK]

Common Mistakes:

• Confusing if-else with loops
• Thinking if-else defines functions
• Mixing if-else with variable declaration

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

easy

A. if x > 10 { fmt.Println("Big") } else { fmt.Println("Small") }

B. if (x > 10) then { fmt.Println("Big") } else { fmt.Println("Small") }

C. if x > 10: fmt.Println("Big") else: fmt.Println("Small")

D. if x > 10 { fmt.Println("Big") } elseif { fmt.Println("Small") }

Solution

1. Step 1: Check Go if-else syntax

   Go uses braces {} for blocks and no parentheses or colons around conditions.

2. Step 2: Identify correct syntax

   if x > 10 { fmt.Println("Big") } else { fmt.Println("Small") } matches Go syntax exactly. Options A, B, and D use wrong keywords or punctuation.

3. Final Answer:

   if x > 10 { fmt.Println("Big") } else { fmt.Println("Small") } -> Option A

4. Quick Check:

   Go if-else uses braces {} [OK]

Hint: Remember: Go uses braces, no then or colons [OK]

Common Mistakes:

• Using 'then' keyword
• Adding colons after conditions
• Writing 'elseif' instead of 'else if'

3. What will this Go code print?

package main
import "fmt"
func main() {
  x := 5
  if x > 10 {
    fmt.Println("Greater")
  } else {
    fmt.Println("Smaller or equal")
  }
}

medium

A. Greater

B. Smaller or equal

C. 5

D. No output

Solution

1. Step 1: Check the value of x

   x is assigned 5, which is not greater than 10.

2. Step 2: Follow the if-else logic

   Since x > 10 is false, the else block runs, printing "Smaller or equal".

3. Final Answer:

   Smaller or equal -> Option B

4. Quick Check:

   5 > 10? No, print else [OK]

Hint: Check condition truth, then pick output [OK]

Common Mistakes:

• Assuming 5 is greater than 10
• Confusing if and else blocks
• Expecting variable value as output

4. Find the error in this Go code:

package main
import "fmt"
func main() {
  x := 7
  if x > 5
    fmt.Println("Big")
  else
    fmt.Println("Small")
}

medium

A. Missing braces {} around if and else blocks

B. Wrong import statement

C. Variable x not declared

D. Missing semicolon after if condition

Solution

1. Step 1: Check if-else block syntax

   In Go, if and else blocks must use braces {} to group statements.

2. Step 2: Identify missing braces

   The code lacks braces around the print statements, causing a syntax error.

3. Final Answer:

   Missing braces {} around if and else blocks -> Option A

4. Quick Check:

   Go requires braces for blocks [OK]

Hint: Always use braces {} for if and else blocks [OK]

Common Mistakes:

• Omitting braces in if-else
• Thinking semicolons are needed after conditions
• Confusing import errors with syntax errors

5. You want to print "Even" if a number is even, otherwise print "Odd". Which Go code correctly does this?

hard

A. if num % 2 = 0 { fmt.Println("Even") } else { fmt.Println("Odd") }

B. if num / 2 == 0 { fmt.Println("Even") } else { fmt.Println("Odd") }

C. if num % 2 == 0 { fmt.Println("Even") } else { fmt.Println("Odd") }

D. if num % 2 != 0 { fmt.Println("Even") } else { fmt.Println("Odd") }

Solution

1. Step 1: Understand how to check even numbers

   A number is even if remainder when divided by 2 is zero (num % 2 == 0).

2. Step 2: Check each option's condition

   if num % 2 == 0 { fmt.Println("Even") } else { fmt.Println("Odd") } uses correct equality check. if num / 2 == 0 { fmt.Println("Even") } else { fmt.Println("Odd") } divides instead of modulo. if num % 2 = 0 { fmt.Println("Even") } else { fmt.Println("Odd") } uses assignment (=) instead of comparison (==). if num % 2 != 0 { fmt.Println("Even") } else { fmt.Println("Odd") } reverses logic.

3. Final Answer:

   if num % 2 == 0 { fmt.Println("Even") } else { fmt.Println("Odd") } -> Option C

4. Quick Check:

   Modulo equals zero means even [OK]

Hint: Use modulo % and == 0 to check even [OK]

Common Mistakes:

• Using / instead of %
• Using = instead of ==
• Reversing condition logic