Operator precedence and evaluation order in C Sharp (C#) - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of mixed arithmetic and logical operators

What is the output of the following C# code snippet?

C Sharp (C#)

int a = 5;
int b = 3;
bool result = a > 2 && b < 5 || a == 5;
Console.WriteLine(result);

A False

B True

C Compilation error

D Runtime exception

💡 Hint

Remember that && has higher precedence than || in C#.

The expression evaluates as (a > 2 && b < 5) || a == 5. Both a > 2 and b < 5 are true, so the left side is true. The right side a == 5 is also true. True || True is True.

❓ Predict Output

intermediate

Result of combined increment operators

What is the value of variable x after executing this code?

C Sharp (C#)

int x = 3;
int y = x++ + ++x;
// What is the value of x now?
Console.WriteLine(x);

A 5

B 6

C 3

D 4

💡 Hint

Remember how postfix and prefix increments work and their evaluation order.

x starts at 3. x++ uses 3 then increments to 4. ++x increments to 5 then uses 5. So y = 3 + 5 = 8. After this, x is 5.

❓ Predict Output

advanced

Output of bitwise and logical operators combined

What is the output of this code snippet?

C Sharp (C#)

int a = 6; // binary 0110
int b = 3; // binary 0011
bool result = (a & b) > 0 && (a | b) < 10;
Console.WriteLine(result);

A Runtime exception

B False

C Compilation error

D True

💡 Hint

Bitwise & and | have lower precedence than comparison operators.

a & b = 2 (binary 0010), which is > 0 (true). a | b = 7 (binary 0111), which is < 10 (true). True && True is True.

❓ Predict Output

advanced

Value of variable after complex expression with ternary and arithmetic

What is the value of z after running this code?

C Sharp (C#)

int x = 4;
int y = 2;
int z = x > y ? x++ * 2 : y++ * 3;
Console.WriteLine(z);

A 8

B 9

C 6

D 10

💡 Hint

The ternary operator evaluates only one branch. Postfix increment happens after the value is used.

x > y is true (4 > 2). So z = x++ * 2 = 4 * 2 = 8. After this, x becomes 5.

❓ Predict Output

expert

Output of expression with mixed assignment and logical operators

What is the output of this code?

C Sharp (C#)

bool a = false;
bool b = true;
bool c = a = b || a && !b;
Console.WriteLine(c);

A Compilation error

B False

C True

D Runtime exception

💡 Hint

Remember operator precedence: && before ||, and assignment is right to left.

Evaluate a && !b first: false && false = false. Then b || false = true || false = true. Then a = true, so c = true.

Practice

1. Which operator has the highest precedence in the expression 3 + 4 * 2?

easy

A. Subtraction (-)

B. Addition (+)

C. Division (/)

D. Multiplication (*)

Solution

1. Step 1: Recall operator precedence rules

   Multiplication (*) has higher precedence than addition (+) in C#.

2. Step 2: Apply precedence to the expression

   The multiplication 4 * 2 is evaluated first, then 3 is added.

3. Final Answer:

   Multiplication (*) -> Option D

4. Quick Check:

   Multiplication before addition = Multiplication (*) [OK]

Hint: Multiplication and division come before addition and subtraction [OK]

Common Mistakes:

• Thinking addition happens before multiplication
• Ignoring operator precedence
• Assuming left-to-right always applies

2. Which of the following expressions is correctly using parentheses to change the evaluation order in C#?

easy

A. int result = 3 + 4 * 2);

B. int result = (3 + 4 * 2;

C. int result = 3 + (4 * 2);

D. int result = 3 + 4 * 2;

Solution

1. Step 1: Check parentheses balance and syntax

   int result = 3 + (4 * 2); has balanced parentheses around (4 * 2), which is correct syntax.

2. Step 2: Verify other options for syntax errors

   Options A and C have unbalanced parentheses, and D has no parentheses to change order.

3. Final Answer:

   int result = 3 + (4 * 2); -> Option C

4. Quick Check:

   Balanced parentheses change order correctly [OK]

Hint: Parentheses must be balanced and properly placed [OK]

Common Mistakes:

• Leaving parentheses unbalanced
• Placing parentheses incorrectly
• Forgetting to close parentheses

3. What is the output of the following C# code?

int a = 5;
int b = 3;
int c = 2;
int result = a - b + c * 4;
Console.WriteLine(result);

medium

A. 10

B. 8

C. 6

D. 4

Solution

1. Step 1: Identify operator precedence in the expression

   Multiplication (*) has higher precedence than addition (+) and subtraction (-), so c * 4 is evaluated first: 2 * 4 = 8.

2. Step 2: Evaluate the remaining expression left to right

   Now compute a - b + 8: 5 - 3 = 2, then 2 + 8 = 10.

3. Final Answer:

   10 -> Option A

4. Quick Check:

   Multiplication before addition/subtraction [OK]

Hint: Multiply before add or subtract [OK]

Common Mistakes:

• Adding before multiplying
• Ignoring operator precedence
• Calculating left to right without precedence

4. Identify the error in the following C# code snippet:

int x = 10;
int y = 5;
int z = x / y * 2 +;
Console.WriteLine(z);

medium

A. Division operator '/' is invalid here

B. Missing operand after '+' operator

C. Variables x and y are not declared

D. Console.WriteLine syntax is incorrect

Solution

1. Step 1: Check the expression for syntax errors

   The expression ends with a '+' operator without a following operand, which is invalid syntax.

2. Step 2: Verify other parts of the code

   Variables x and y are declared correctly, division operator is valid, and Console.WriteLine syntax is correct.

3. Final Answer:

   Missing operand after '+' operator -> Option B

4. Quick Check:

   Operator must have operands on both sides [OK]

Hint: Check for missing operands near operators [OK]

Common Mistakes:

• Ignoring incomplete expressions
• Assuming division operator is wrong
• Overlooking missing semicolons

5. Given the code below, what is the value of result? Consider operator precedence and evaluation order.

int a = 2;
int b = 3;
int c = 4;
int result = a + b * c - (a + b) * c / b;

hard

A. 8

B. 4

C. 6

D. 2

Solution

1. Step 1: Evaluate expressions inside parentheses first

   (a + b) = 2 + 3 = 5.

2. Step 2: Calculate multiplication and division next

   b * c = 3 * 4 = 12.
   (a + b) * c / b = 5 * 4 / 3 = 20 / 3 = 6 (integer division truncates).

3. Step 3: Calculate the full expression left to right

   a + b * c - (a + b) * c / b = 2 + 12 - 6 = 14 - 6 = 8.

4. Step 4: Re-check integer division

   20 / 3 = 6 (integer division truncates decimals).

5. Final Answer:

   8 -> Option A

6. Quick Check:

   Parentheses first, then multiply/divide, then add/subtract [OK]

Hint: Parentheses first, then multiply/divide, then add/subtract [OK]

Common Mistakes:

• Ignoring integer division truncation
• Evaluating left to right without precedence
• Calculating parentheses last