If–else statement in Go - Step-by-Step Execution

Concept Flow - If–else statement

Evaluate condition

↓

Condition true?

No→Execute else block

Yes↓

Execute if block

↓

End

The program checks a condition. If true, it runs the 'if' block; otherwise, it runs the 'else' block.

Execution Sample

Go

package main
import "fmt"
func main() {
  x := 10
  if x > 5 {
    fmt.Println("x is greater than 5")
  } else {
    fmt.Println("x is 5 or less")
  }
}

This code checks if x is greater than 5 and prints a message accordingly.

Execution Table

Step	Condition	Result	Branch Taken	Output
1	x > 5 (10 > 5)	true	if block	"x is greater than 5" printed
2	End of if-else	N/A	Program ends	No further output

💡 Condition true at step 1, so if block executed; program ends after printing.

Variable Tracker

Variable	Start	After Step 1	Final
x	undefined	10	10

Key Moments - 2 Insights

Why does the program print "x is greater than 5" and not the else message?

Because at step 1 in the execution table, the condition x > 5 is true (10 > 5), so the if block runs, skipping the else block.

What happens if the condition is false?

If the condition were false, the else block would run instead, as shown in the 'Branch Taken' column for the else path.

Visual Quiz - 3 Questions

Look at the execution table, what is the condition result at step 1?

A undefined

B true

C false

D error

💡 Hint

Check the 'Result' column in the first row of the execution table.

At which step does the program decide which branch to take?

A Step 2

B Before Step 1

C Step 1

D After Step 2

💡 Hint

Look at the 'Condition' and 'Branch Taken' columns in the execution table.

If x was 3 instead of 10, what would the output be according to the execution flow?

A "x is 5 or less"

B "x is greater than 5"

C No output

D Program error

💡 Hint

Think about the condition x > 5 and which branch runs when false.

Concept Snapshot

if condition {
  // code runs if condition true
} else {
  // code runs if condition false
}
Checks condition once, runs one block only.

Full Transcript

This visual trace shows how an if-else statement works in Go. The program sets x to 10. It then checks if x is greater than 5. Since 10 is greater than 5, the condition is true, so the program runs the code inside the if block and prints "x is greater than 5". The else block is skipped. The variable x stays 10 throughout. If the condition were false, the else block would run instead. This helps the program choose between two paths based on a condition.

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