Reusability and maintenance - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a reusable function that adds two integers.

C

int add(int a, int b) {
    return 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 or multiplication instead of addition.

Forgetting to return the result.

The + operator adds two integers, which is what the function should do.

2fill in blank

medium

Complete the code to call the function add with arguments 5 and 3.

C

int result = [1](5, 3);

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

Aadd

Bsum

Ccalculate

Dtotal

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different function name that does not exist.

Forgetting to use parentheses for the function call.

The function is named add, so calling add(5, 3) is correct.

3fill in blank

hard

Fix the error in the function prototype to ensure proper reusability.

C

int [1](int a, int b);

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

AaddNumbers

BAdd

Cadd

Daddition

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different or capitalized function name.

Mismatching the prototype and definition names.

The function prototype must match the function name exactly, which is add.

4fill in blank

hard

Fill both blanks to create a reusable function that multiplies two numbers and returns the result.

C

int [1](int x, int y) {
    return x [2] y;
}

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

Amultiply

B+

C*

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using addition or subtraction instead of multiplication.

Using a function name that does not describe multiplication.

The function name multiply describes the operation, and the * operator multiplies the two numbers.

5fill in blank

hard

Fill all three blanks to create a reusable function that checks if a number is even and returns 1 if true, else 0.

C

int [1](int num) {
    if (num [2] 2 [3] 0) {
        return 1;
    } else {
        return 0;
    }
}

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

AisEven

B%

C==

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect operators like != instead of ==.

Choosing a function name that does not describe the check.

The function name isEven clearly states its purpose. The modulus operator % checks the remainder, and == compares it to zero to determine evenness.

Practice

1. What is the main benefit of using functions in C for reusability and maintenance?

easy

A. Functions use less memory than variables

B. Functions make the program run faster

C. You can write code once and use it many times

D. Functions prevent all bugs automatically

Solution

1. Step 1: Understand the purpose of functions

   Functions allow you to group code that performs a task so you can reuse it multiple times without rewriting.

2. Step 2: Connect reusability to maintenance

   Using functions reduces repeated code, making it easier to update and maintain.

3. Final Answer:

   You can write code once and use it many times -> Option C

4. Quick Check:

   Functions improve reusability = You can write code once and use it many times [OK]

Hint: Functions let you reuse code easily [OK]

Common Mistakes:

• Thinking functions always make code faster
• Confusing functions with variables
• Believing functions fix all bugs automatically

2. Which of the following is the correct syntax to declare a function named add that takes two integers and returns an integer in C?

easy

A. int add(int a, int b);

B. add int(int a, int b);

C. int add(a, b) int a; int b; { return a + b; }

D. function add(int a, int b) { return a + b; }

Solution

1. Step 1: Identify correct function declaration syntax

   In C, a function declaration specifies the return type, function name, and parameter types inside parentheses.

2. Step 2: Check each option

   int add(int a, int b); matches the correct syntax: int add(int a, int b);. Others have wrong order, keywords, or syntax.

3. Final Answer:

   int add(int a, int b); -> Option A

4. Quick Check:

   Correct C function declaration = int add(int a, int b); [OK]

Hint: Function declarations start with return type and name [OK]

Common Mistakes:

• Using 'function' keyword (not in C)
• Wrong parameter syntax
• Missing return type

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

int square(int x) {
    return x * x;
}

int main() {
    int result = square(4);
    printf("%d", result);
    return 0;
}

medium

A. Compilation error

B. 8

C. 4

D. 16

Solution

1. Step 1: Understand the function behavior

   The function square returns the input multiplied by itself, so square(4) returns 16.

2. Step 2: Check the main function output

   The main function calls square(4), stores 16 in result, and prints it with printf.

3. Final Answer:

   16 -> Option D

4. Quick Check:

   square(4) = 16 [OK]

Hint: Multiply input by itself to find square [OK]

Common Mistakes:

• Confusing multiplication with addition
• Expecting 8 instead of 16
• Thinking code has syntax errors

4. Identify the error in the following C code that tries to reuse a function:

int multiply(int a, int b) {
    return a * b;
}

int main() {
    int result = multiply(5);
    printf("%d", result);
    return 0;
}

medium

A. multiply is called with only one argument instead of two

B. main function should return void

C. printf format specifier is incorrect

D. Function multiply is missing a return statement

Solution

1. Step 1: Check function definition and call

   The function multiply requires two integer arguments, but in main it is called with only one argument.

2. Step 2: Identify the error type

   This mismatch causes a compilation error because the number of arguments does not match the function signature.

3. Final Answer:

   multiply is called with only one argument instead of two -> Option A

4. Quick Check:

   Argument count mismatch = multiply is called with only one argument instead of two [OK]

Hint: Match function call arguments to definition [OK]

Common Mistakes:

• Ignoring argument count mismatch
• Thinking printf format is wrong
• Assuming main must return void

5. You want to write a reusable function in C that calculates the average of an array of integers. Which approach improves reusability and maintenance the most?

hard

A. Write the average calculation code inside main() every time you need it

B. Create a function that takes an integer array and its size, then returns the average

C. Use global variables to store the array and size, then write a function without parameters

D. Copy and paste the average calculation code wherever needed

Solution

1. Step 1: Understand reusability principles

   Reusable code should be modular, accept inputs, and avoid global state to be flexible and maintainable.

2. Step 2: Evaluate each option

   Create a function that takes an integer array and its size, then returns the average creates a function with parameters for array and size, making it reusable for any array. Others either duplicate code or rely on globals, reducing reusability.

3. Final Answer:

   Create a function that takes an integer array and its size, then returns the average -> Option B

4. Quick Check:

   Function with parameters improves reusability = Create a function that takes an integer array and its size, then returns the average [OK]

Hint: Functions with parameters are reusable and maintainable [OK]

Common Mistakes:

• Using global variables reduces flexibility
• Duplicating code increases errors
• Writing code only inside main limits reuse