Intro to C Workshop – Practice Questions

Link to presentation: Intro to C Workshop – Presentation

Complete each of the following questions in C.

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Question 1 – Hello World

Create a program which prints:

Hello World!

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Question 2 – User Input (Integer)

Create a program which:

1. Asks the user to input an integer.
2. Prints the integer back to the screen.

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Question 3 – Area of a Circle

Create a program which:

1. Defines a float p as the value of π (PI) to 3 decimal places.
2. Asks the user to input a radius.
3. Calculates the area of the circle.
4. Prints the result to 3 decimal places.

Formula for the area of a circle:

Area = p * r²

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Question 4 – Countdown with Loops and Arrays

Create a program which:

1. Prints the word countdown.
2. Prints a countdown from 5 to 1.
3. Uses loops and arrays.

Example output:

countdown
5
4
3
2
1

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Question 5 – Printing Your Name

Create a program which prints your name using:

• Loops
• Strings

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Question 6 – Pointers Only

Create a program which prints the integer:

10

You must use only pointers and addresses to accomplish this.

(No direct printing of the number is allowed.)

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Question 7 – Functions and Pointers

Create a program which:

1. Starts with a value of 20.
2. Uses a void function named divide_by_10.
3. Divides the value by 10 using pointers and addresses.
4. Prints the value before and after the division.

Function prototype:

void divide_by_10(float *value);

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Question 8 – Structures

Create a structure that allows tracking employees in a company with:

• Name
• Employee ID
• Department
• Salary

Then print each employee’s:

• Employee ID
• Department
• Salary

Use the following employees:

Name	ID	Department	Salary
Bob	30894	HR	83000
Megan	29836	Marketing	85900
Steph	98763	IT	92500
Mo	93087	IT	93840

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Question 9 – Dynamic Memory Allocation (malloc and free)

Create a program which:

1. Asks the user how many integers they want to store.
2. Dynamically allocates enough memory to store that many integers using malloc.
3. Uses a loop to let the user input each integer.
4. Prints all the integers back to the screen.
5. Frees the allocated memory using free.

Rules:

• You must use malloc to allocate the array.
• You must check that malloc was successful.
• You must use free before the program exits.

Example run:

How many numbers do you want to store? 4
Enter number 1: 10
Enter number 2: 25
Enter number 3: 7
Enter number 4: 42

You entered:
10
25
7
42