Operator precedence in Go - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to correctly calculate the result using operator precedence.

Go

result := 3 + 4 * [1]

Drag options to blanks, or click blank then click option'

A2

B5

C1

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Adding 3 + 4 first, then multiplying by 5.

Ignoring operator precedence.

The multiplication happens before addition, so 4 * 5 = 20, then 3 + 20 = 23.

2fill in blank

medium

Complete the code to correctly evaluate the expression with mixed operators.

Go

result := (10 - 2) / [1] + 3

Drag options to blanks, or click blank then click option'

A4

B3

C1

D2

Attempts:

3 left

💡 Hint

Common Mistakes

Dividing before subtracting inside parentheses.

Adding before division.

Parentheses first: 10 - 2 = 8. Then division: 8 / 2 = 4. Finally addition: 4 + 3 = 7.

3fill in blank

hard

Fix the error in the expression to get the correct result.

Go

result := 5 + 3 * 2 [1] 4

Drag options to blanks, or click blank then click option'

A-

B+

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using '+' instead of '-' causing wrong final result.

Ignoring operator precedence.

Multiplication first: 3 * 2 = 6. Then addition: 5 + 6 = 11. Finally subtraction: 11 - 4 = 7.

4fill in blank

hard

Fill both blanks to correctly compute the expression with operator precedence.

Go

result := (8 [1] 4) [2] 2

Drag options to blanks, or click blank then click option'

A+

B-

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using '+' instead of '-' inside parentheses.

Dividing instead of multiplying after parentheses.

First, inside parentheses: 8 - 4 = 4. Then multiply by 2: 4 * 2 = 8.

5fill in blank

hard

Fill all three blanks to correctly evaluate the complex expression.

Go

result := (6 [1] 2) [2] (3 [3] 1)

Drag options to blanks, or click blank then click option'

A+

B*

C-

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using '-' instead of '+' in the first parentheses.

Using '-' instead of '/' in the second parentheses.

Adding instead of multiplying the two parentheses results.

Calculate inside parentheses: 6 + 2 = 8 and 3 / 1 = 3. Then multiply: 8 * 3 = 24.

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