Why C is widely used - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to print "Hello, World!" in C.

C

#include <stdio.h>

int main() {
    [1]("Hello, World!\n");
    return 0;
}

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

Aprint

Bprintf

Cecho

Dcout

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'print' or 'echo' which are not C functions.

The printf function is used in C to print text to the screen.

2fill in blank

medium

Complete the code to declare an integer variable named 'count' in C.

C

[1] count = 10;

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

Aint

Bfloat

Cstring

Dchar

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'float' for integers or 'string' which is not a C type.

In C, int is used to declare integer variables.

3fill in blank

hard

Fix the error in the code to correctly include the standard input/output header.

C

#include [1]

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

A<stdio>

B"stdio"

C"stdio.h"

D<stdio.h>

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes instead of angle brackets or missing '.h' extension.

The correct way to include the standard input/output header in C is #include <stdio.h>.

4fill in blank

hard

Fill both blanks to declare a pointer to an integer and assign it the address of variable 'num'.

C

int num = 5;
[1] *ptr;
ptr = [2];

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

Aint

B&num

Cnum

Dfloat

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning the value instead of the address to the pointer.

To declare a pointer to an integer, use int *ptr;. To assign it the address of 'num', use ptr = #.

5fill in blank

hard

Fill all three blanks to define a function named 'add' that takes two integers and returns their sum.

C

[1] add([2] a, [3] b) {
    return a + b;
}

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

Aint

Dvoid

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'void' as return type or parameter types.

The function 'add' returns an integer and takes two integer parameters.

Practice

1. Why is the C programming language widely used in system software development?

easy

A. Because it is fast and works close to the computer's hardware

B. Because it has a built-in graphical user interface

C. Because it automatically manages memory for the programmer

D. Because it is only used for web development

Solution

1. Step 1: Understand C's speed and hardware access

   C is designed to be fast and allows direct access to memory and hardware, which is essential for system software.

2. Step 2: Compare with other options

   Options A, B, and C are incorrect because C is not only for web development (A), does not have built-in GUI (B), and does not automatically manage memory (C).

3. Final Answer:

   Because it is fast and works close to the computer's hardware -> Option A

4. Quick Check:

   Speed and hardware access = D [OK]

Hint: Remember: C is close to hardware and very fast [OK]

Common Mistakes:

• Thinking C has automatic memory management
• Confusing C with languages made for web or GUI
• Assuming C is slow or high-level only

2. Which of the following is the correct way to declare an integer variable in C?

easy

A. integer number;

B. int number;

C. num int;

D. var number;

Solution

1. Step 1: Recall C syntax for variable declaration

   In C, the keyword int is used to declare integer variables, followed by the variable name and a semicolon.

2. Step 2: Check each option

   Only int number; uses the correct syntax: int number;. Others use incorrect keywords or order.

3. Final Answer:

   int number; -> Option B

4. Quick Check:

   Correct int declaration = A [OK]

Hint: Use 'int' keyword for integers in C [OK]

Common Mistakes:

• Using 'integer' instead of 'int'
• Placing type after variable name
• Using 'var' keyword (not in C)

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

int main() {
    int a = 5;
    int b = 3;
    int c = a + b * 2;
    printf("%d", c);
    return 0;
}

medium

A. 16

B. 13

C. 11

D. 10

Solution

1. Step 1: Understand operator precedence in the expression

   Multiplication (*) has higher precedence than addition (+), so b * 2 is calculated first: 3 * 2 = 6.

2. Step 2: Calculate the final value of c

   Then add a: 5 + 6 = 11.

3. Final Answer:

   11 -> Option C

4. Quick Check:

   5 + (3 * 2) = 11 [OK]

Hint: Remember multiplication before addition in expressions [OK]

Common Mistakes:

• Adding before multiplying
• Confusing operator precedence
• Misreading variable values

4. Identify the error in this C code snippet:

int main() {
    int x = 10
    printf("%d", x);
    return 0;
}

medium

A. Missing semicolon after variable declaration

B. Incorrect printf format specifier

C. Variable x is not declared

D. Missing return statement

Solution

1. Step 1: Check syntax line by line

   The line int x = 10 is missing a semicolon at the end, which is required in C.

2. Step 2: Verify other parts

   The printf format specifier %d matches the integer variable, variable x is declared, and return statement is present.

3. Final Answer:

   Missing semicolon after variable declaration -> Option A

4. Quick Check:

   Semicolon missing after int x = 10 [OK]

Hint: Check for missing semicolons after statements [OK]

Common Mistakes:

• Ignoring missing semicolon errors
• Assuming printf format is wrong
• Thinking return statement is optional

5. You want to write a C program that needs to run very fast and control hardware directly. Which feature of C helps achieve this best?

hard

A. Automatic garbage collection

B. Built-in support for web APIs

C. Dynamic typing of variables

D. Low-level memory access using pointers

Solution

1. Step 1: Identify features that allow hardware control

   C allows direct memory access through pointers, which lets programmers control hardware and memory precisely.

2. Step 2: Eliminate incorrect options

   Automatic garbage collection and dynamic typing are not features of C, and built-in web API support is unrelated to hardware control.

3. Final Answer:

   Low-level memory access using pointers -> Option D

4. Quick Check:

   Pointers enable hardware control = C [OK]

Hint: Pointers give direct memory control in C [OK]

Common Mistakes:

• Confusing C with languages that have garbage collection
• Thinking C supports dynamic typing
• Assuming C has built-in web features