Operator precedence in Go - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Go code involving mixed operators?

Consider the following Go code snippet. What will it print?

Go

package main
import "fmt"
func main() {
    result := 3 + 4*2
    fmt.Println(result)
}

A 14

B 11

C 10

D 7

💡 Hint

Remember that multiplication (*) has higher precedence than addition (+).

Multiplication happens before addition, so 4*2 = 8, then 3 + 8 = 11.

❓ Predict Output

intermediate

What is the output of this Go code with parentheses changing precedence?

What will this Go program print?

Go

package main
import "fmt"
func main() {
    result := (3 + 4) * 2
    fmt.Println(result)
}

A 14

B 7

C 10

D 11

💡 Hint

Parentheses change the order of operations.

Parentheses force addition first: (3 + 4) = 7, then multiply by 2 = 14.

❓ Predict Output

advanced

What is the output of this Go code with mixed logical and comparison operators?

What will this Go program print?

Go

package main
import "fmt"
func main() {
    a := 5
    b := 10
    c := 15
    result := a < b && b > c || c == 15
    fmt.Println(result)
}

A true

B false

C compile error

D panic

💡 Hint

Logical AND (&&) has higher precedence than logical OR (||).

Evaluate a < b && b > c first: 5 < 10 is true, 10 > 15 is false, so true && false = false.
Then false || c == 15: c == 15 is true, so false || true = true.

❓ Predict Output

advanced

What is the output of this Go code with bitwise and arithmetic operators?

What will this Go program print?

Go

package main
import "fmt"
func main() {
    x := 6  // binary 110
    y := 3  // binary 011
    result := x & y + 2
    fmt.Println(result)
}

A 2

B 6

C 4

D 0

💡 Hint

Bitwise AND (&) has higher precedence than addition (+).

First compute x & y: 6 & 3 = 2 (binary 110 & 011 = 010). Then add 2: 2 + 2 = 4.

❓ Predict Output

expert

What is the output of this Go code with mixed assignment and arithmetic operators?

What will this Go program print?

Go

package main
import "fmt"
func main() {
    a := 10
    b := 5
    a += b * 2
    fmt.Println(a)
}

A 25

B 30

C 15

D 20

💡 Hint

Multiplication happens before the addition assignment.

b * 2 is evaluated first: 5 * 2 = 10. Then a += 10 means a = a + 10 = 10 + 10 = 20.

Practice

1. In Go, which operator has the highest precedence among these: +, -, *, /?

easy

A. Subtraction (-)

B. Addition (+)

C. All have the same precedence

D. Multiplication (*) and division (/)

Solution

1. Step 1: Recall operator precedence rules in Go

   Multiplication (*) and division (/) have higher precedence than addition (+) and subtraction (-).

2. Step 2: Compare given operators

   Among the given operators, * and / are evaluated before + and -.

3. Final Answer:

   Multiplication (*) and division (/) -> Option D

4. Quick Check:

   *, / > +, - [OK]

Hint: Remember: multiply/divide before add/subtract [OK]

Common Mistakes:

• Thinking all operators have equal precedence
• Confusing addition with multiplication precedence
• Ignoring division operator precedence

2. Which of the following Go expressions is syntactically correct and respects operator precedence?

easy

A. result := 5 + (3 * 2

B. result := 5 + * 3 2

C. result := 5 + 3 * 2

D. result := 5 + 3 * * 2

Solution

1. Step 1: Check each expression for syntax correctness

   result := 5 + 3 * 2 uses valid operators and correct syntax. Options B, C, and D have syntax errors like misplaced operators or missing parentheses.

2. Step 2: Confirm operator precedence in result := 5 + 3 * 2

   Multiplication (*) happens before addition (+), so expression is valid and respects precedence.

3. Final Answer:

   result := 5 + 3 * 2 -> Option C

4. Quick Check:

   Valid syntax and precedence in result := 5 + 3 * 2 [OK]

Hint: Check for misplaced or missing operators and parentheses [OK]

Common Mistakes:

• Using two operators in a row without operand
• Missing closing parentheses
• Confusing operator placement

3. What is the output of this Go code?

package main
import "fmt"
func main() {
    x := 2 + 3 * 4 - 6 / 2
    fmt.Println(x)
}

medium

A. 11

B. 10

C. 12

D. 14

Solution

1. Step 1: Apply operator precedence to expression

   Multiplication and division first: 3 * 4 = 12, 6 / 2 = 3.

2. Step 2: Calculate addition and subtraction left to right

   Expression becomes 2 + 12 - 3 = 14 - 3 = 11.

3. Final Answer:

   11 -> Option A

4. Quick Check:

   2 + (3*4) - (6/2) = 11 [OK]

Hint: Do * and / before + and -, then left to right [OK]

Common Mistakes:

• Adding before multiplying
• Subtracting before division
• Ignoring left-to-right evaluation for + and -

4. Identify the error in this Go code snippet related to operator precedence:

package main
import "fmt"
func main() {
    result := 10 / 2 * 3
    + 4 - 1
    fmt.Println(result)
}

medium

A. Line break splits expression incorrectly without continuation

B. Division operator has lower precedence than multiplication

C. Missing parentheses around addition and subtraction

D. Using + and - operators together causes syntax error

Solution

1. Step 1: Check expression syntax across lines

   The expression is split across two lines without proper continuation, causing a syntax error.

2. Step 2: Understand Go line continuation rules

   Go requires expressions split across lines to be clearly continued, usually by operators at line end or parentheses.

3. Final Answer:

   Line break splits expression incorrectly without continuation -> Option A

4. Quick Check:

   Line breaks need proper continuation [OK]

Hint: Avoid breaking expressions without operators or parentheses [OK]

Common Mistakes:

• Assuming operator precedence causes error
• Thinking + and - together cause syntax error
• Ignoring Go's line continuation rules

5. Given the Go expression:

result := 8 + 2 * (5 - 3) / 2 - 1

What is the correct value of result after evaluation?

hard

A. 8

B. 9

C. 10

D. 11

Solution

1. Step 1: Evaluate parentheses first

   (5 - 3) = 2.

2. Step 2: Apply multiplication and division left to right

   2 * 2 = 4, then 4 / 2 = 2.

3. Step 3: Perform addition and subtraction left to right

   8 + 2 = 10, then 10 - 1 = 9.

4. Final Answer:

   9 -> Option B

5. Quick Check:

   8 + 2*(2)/2 - 1 = 9 [OK]

Hint: Calculate parentheses first, then * /, then + - left to right [OK]

Common Mistakes:

• Ignoring parentheses priority
• Doing addition before multiplication
• Dividing before multiplying inside parentheses