Logical operators in Go - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of combined logical operators

What is the output of this Go program?

package main
import "fmt"
func main() {
  a := true
  b := false
  c := true
  fmt.Println(a && b || c)
}

Go

package main
import "fmt"
func main() {
  a := true
  b := false
  c := true
  fmt.Println(a && b || c)
}

A true

B panic at runtime

C Compilation error

D false

💡 Hint

Remember that && has higher precedence than || in Go.

The expression evaluates as (a && b) || c. Since a && b is false, and c is true, the whole expression is true.

❓ Predict Output

intermediate

Result of negation and OR operator

What will this Go code print?

package main
import "fmt"
func main() {
  x := false
  y := true
  fmt.Println(!x || y)
}

Go

package main
import "fmt"
func main() {
  x := false
  y := true
  fmt.Println(!x || y)
}

A true

B false

C Compilation error

D panic at runtime

💡 Hint

Negation (!) flips the boolean value.

Negation of false is true, so !x is true. true || y is true.

❓ Predict Output

advanced

Output of chained logical operators with variables

What is the output of this Go program?

package main
import "fmt"
func main() {
  a := false
  b := false
  c := true
  d := true
  fmt.Println(a || b && c && d)
}

Go

package main
import "fmt"
func main() {
  a := false
  b := false
  c := true
  d := true
  fmt.Println(a || b && c && d)
}

A Compilation error

B true

C false

D panic at runtime

💡 Hint

Remember operator precedence: && before ||.

b && c && d is false because b is false. a || false is false.

❓ Predict Output

advanced

Output of logical AND with short-circuit

What does this Go code print?

package main
import "fmt"
func main() {
  x := false
  y := true
  fmt.Println(x && y)
}

Go

package main
import "fmt"
func main() {
  x := false
  y := true
  fmt.Println(x && y)
}

A true

B Compilation error

C panic at runtime

D false

💡 Hint

Logical AND returns false if the first operand is false.

Since x is false, x && y is false without evaluating y.

❓ Predict Output

expert

Output of complex logical expression with parentheses

What is the output of this Go program?

package main
import "fmt"
func main() {
  a := true
  b := false
  c := true
  d := false
  fmt.Println((a || b) && (c && !d))
}

Go

package main
import "fmt"
func main() {
  a := true
  b := false
  c := true
  d := false
  fmt.Println((a || b) && (c && !d))
}

A false

B true

C Compilation error

D panic at runtime

💡 Hint

Evaluate inside parentheses first, then combine.

(a || b) is true, (c && !d) is true, so true && true is true.

Practice

1. Which logical operator in Go means AND and returns true only if both conditions are true?

easy

A. !

B. ||

C. &

D. &&

Solution

1. Step 1: Understand the meaning of logical AND

   The AND operator returns true only when both conditions it connects are true.

2. Step 2: Identify Go's AND operator

   In Go, the AND operator is written as &&, which matches the description.

3. Final Answer:

   && -> Option D

4. Quick Check:

   AND = && [OK]

Hint: AND is &&, OR is ||, NOT is ! [OK]

Common Mistakes:

• Confusing & (bitwise AND) with && (logical AND)
• Mixing OR (||) with AND (&&)
• Using ! as AND operator

2. Which of the following is the correct syntax for the logical NOT operator in Go?

easy

A. not x

B. !x

C. ~x

D. x!

Solution

1. Step 1: Recall Go syntax for logical NOT

   In Go, the logical NOT operator is a single exclamation mark placed before the variable or expression.

2. Step 2: Match options with correct syntax

   !x uses !x, which is the correct syntax for NOT in Go.

3. Final Answer:

   !x -> Option B

4. Quick Check:

   NOT = ! [OK]

Hint: NOT always uses ! before the condition [OK]

Common Mistakes:

• Writing 'not x' like in some other languages
• Using ~ which is bitwise NOT, not logical NOT
• Placing ! after the variable

3. What is the output of this Go code snippet?

package main
import "fmt"
func main() {
    a := true
    b := false
    fmt.Println(a && !b || b)
}

medium

A. true

B. false

C. Syntax error

D. Compilation error

Solution

1. Step 1: Evaluate !b

   b is false, so !b is true.

2. Step 2: Evaluate a && !b

   a is true and !b is true, so a && !b is true.

3. Step 3: Evaluate (a && !b) || b

   true || false is true.

4. Final Answer:

   true -> Option A

5. Quick Check:

   True AND NOT False OR False = True [OK]

Hint: Evaluate NOT first, then AND, then OR [OK]

Common Mistakes:

• Evaluating OR before AND
• Forgetting to negate b
• Assuming false || true is false

4. Identify the error in this Go code snippet:

package main
import "fmt"
func main() {
    x := true
    y := false
    if x & y {
        fmt.Println("Both true")
    }
}

medium

A. Using & instead of && in if condition

B. Missing parentheses around condition

C. fmt.Println syntax error

D. Variable declaration error

Solution

1. Step 1: Check logical operators in if condition

   The code uses & which is bitwise AND, not logical AND.

2. Step 2: Identify correct operator for boolean logic

   Logical AND in Go is &&, so & causes a type error here.

3. Final Answer:

   Using & instead of && in if condition -> Option A

4. Quick Check:

   Logical AND needs &&, not & [OK]

Hint: Use && for logical AND, & is bitwise [OK]

Common Mistakes:

• Using & instead of && for booleans
• Assuming & works like && in conditions
• Ignoring compiler error messages

5. Given a variable score (int), which condition correctly checks if score is between 50 and 100 inclusive using logical operators in Go?

hard

A. score >= 50 || score <= 100

B. score > 50 && score < 100

C. score >= 50 && score <= 100

D. score > 50 || score < 100

Solution

1. Step 1: Understand the range condition

   We want score to be at least 50 and at most 100, so both conditions must be true.

2. Step 2: Choose correct logical operator

   AND (&&) combines conditions that both must be true; OR (||) would allow values outside the range.

3. Step 3: Check inclusivity

   Using >= and <= includes 50 and 100 themselves.

4. Final Answer:

   score >= 50 && score <= 100 -> Option C

5. Quick Check:

   Between means AND, not OR [OK]

Hint: Use && to combine conditions that both must be true [OK]

Common Mistakes:

• Using || which allows values outside range
• Using > and < excludes boundary values
• Confusing AND and OR logic