Why operators are needed in C - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add two numbers and store the result.

C

int a = 5, b = 3;
int sum = a [1] b;

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

A-

B/

C*

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using subtraction - instead of addition.

The plus operator + adds two numbers together.

2fill in blank

medium

Complete the code to check if a number is greater than 10.

C

int num = 15;
if (num [1] 10) {
    // do something
}

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

A>

B<=

C==

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using less than < instead of greater than.

The greater than operator > checks if the left value is bigger than the right.

3fill in blank

hard

Fix the error in the code to multiply two numbers.

C

int x = 4, y = 6;
int product = x [1] y;

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

A*

B+

C-

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using addition + instead of multiplication.

The multiplication operator * multiplies two numbers.

4fill in blank

hard

Fill both blanks to create a condition that checks if a number is between 5 and 10 (inclusive).

C

int val = 7;
if (val [1] 5 && val [2] 10) {
    // inside range
}

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

A>=

B<

C<=

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using > or < which exclude boundaries.

Use >= to check if value is at least 5, and <= to check if it is at most 10.

5fill in blank

hard

Fill all three blanks to calculate the average of three numbers.

C

int a = 4, b = 8, c = 12;
float avg = ([1] + [2] + [3]) / 3.0;

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

Aa

Bb

Cc

Davg

Attempts:

3 left

💡 Hint

Common Mistakes

Using the variable avg inside its own calculation.

The average is the sum of a, b, and c divided by 3.

Practice

1. Why do we need operators in C programming?

easy

A. To perform calculations and compare values

B. To write comments in the code

C. To declare variables

D. To create functions

Solution

1. Step 1: Understand the role of operators

   Operators are symbols that let us do math or compare values in code.

2. Step 2: Identify what operators do in C

   They help perform calculations like addition or check conditions like equality.

3. Final Answer:

   To perform calculations and compare values -> Option A

4. Quick Check:

   Operators = calculations and comparisons [OK]

Hint: Operators do math and comparisons in code [OK]

Common Mistakes:

• Thinking operators declare variables
• Confusing operators with comments
• Believing operators create functions

2. Which of the following is the correct way to use the addition operator in C?

easy

A. int sum = 5 & 3;

B. int sum = 5 plus 3;

C. int sum = 5 + 3;

D. int sum = 5 - 3;

Solution

1. Step 1: Recognize the addition operator syntax

   In C, the plus sign (+) is used to add numbers.

2. Step 2: Check each option for correct syntax

   int sum = 5 + 3; uses '+' correctly; others use wrong symbols or words.

3. Final Answer:

   int sum = 5 + 3; -> Option C

4. Quick Check:

   Use '+' for addition [OK]

Hint: Use '+' symbol for addition in C [OK]

Common Mistakes:

• Writing 'plus' instead of '+'
• Using '&' instead of '+'
• Confusing subtraction '-' with addition '+'

3. What will be the output of this C code?

int a = 10, b = 3;
int result = a / b;
printf("%d", result);

medium

A. 3

B. 3.33

C. 4

D. Error

Solution

1. Step 1: Understand integer division in C

   Dividing two integers returns an integer by dropping the decimal part.

2. Step 2: Calculate 10 divided by 3 as integer division

   10 / 3 equals 3.33 but integer division truncates to 3.

3. Final Answer:

   3 -> Option A

4. Quick Check:

   Integer division truncates decimals [OK]

Hint: Integer division drops decimals, result is integer [OK]

Common Mistakes:

• Expecting decimal output with integer division
• Confusing '/' with modulo operator
• Assuming automatic float conversion

4. Find the error in this C code snippet:

int x = 5;
int y = 10;
if (x = y) {
    printf("Equal");
} else {
    printf("Not Equal");
}

medium

A. The if statement syntax is incorrect

B. The '=' operator should be '==' for comparison

C. The printf statements are missing semicolons

D. The variables x and y are not declared

Solution

1. Step 1: Identify the operator used in the if condition

   The code uses '=' which is assignment, not comparison.

2. Step 2: Correct operator for comparison in C

   Use '==' to compare values, '=' assigns value.

3. Final Answer:

   The '=' operator should be '==' for comparison -> Option B

4. Quick Check:

   Use '==' to compare, '=' to assign [OK]

Hint: Use '==' for comparison, not '=' [OK]

Common Mistakes:

• Using '=' instead of '==' in conditions
• Ignoring missing semicolons (not the error here)
• Confusing assignment with comparison

5. You want to check if a number is even or odd in C. Which operator helps you do this efficiently?

hard

A. The addition operator (+)

B. The logical AND operator (&&)

C. The assignment operator (=)

D. The modulo operator (%)

Solution

1. Step 1: Understand how to check even or odd

   A number is even if dividing by 2 leaves remainder 0, odd otherwise.

2. Step 2: Identify operator that gives remainder

   The modulo operator (%) returns the remainder after division.

3. Final Answer:

   The modulo operator (%) -> Option D

4. Quick Check:

   Use '%' to find remainder for even/odd check [OK]

Hint: Use '%' to check remainder for even or odd [OK]

Common Mistakes:

• Using '+' instead of '%' for remainder
• Confusing assignment '=' with modulo
• Using logical AND '&&' incorrectly here