Exercises L03

Exercise Questions - L-03: Operators, Precedence, Conditionals #

Basic I/O Operations #

Question 1: Simple Output #

Write a C program that displays the following message on the screen:

Welcome to Computer Programming!
This is Lecture 3.

Question 2: Variable Declaration and Output #

Write a C program that:

  • Declares variables for storing your name (string), age (integer), and height (float)
  • Initializes them with appropriate values
  • Prints all three values using printf with proper format specifiers

Question 3: Reading User Input #

Write a C program that:

  • Prompts the user to enter their name, age, and favorite character
  • Reads these values using scanf
  • Displays them back to the user in a formatted manner

Arithmetic Operations #

Question 4: Basic Calculator #

Write a C program that:

  • Takes two integers as input from the user
  • Performs all arithmetic operations (+, -, *, /, %)
  • Displays the results of each operation
  • Handle the case where division by zero might occur

Question 5: Expression Evaluation #

Given the following expression, manually calculate the result and then write a C program to verify your answer:

int a = 15, b = 4, c = 3;
int result = a + b * c - a / b + a % b;

What will be the value of result?

Question 6: Area and Perimeter Calculator #

Write a C program that:

  • Takes length and width of a rectangle as input
  • Calculates and displays the area and perimeter
  • Use appropriate data types for decimal values

Assignment Operations and Swapping #

Question 7: Variable Swapping #

Write a C program that swaps the values of two variables:

  • Method 1: Using a temporary variable (as shown in the lecture)
  • Method 2: Without using a temporary variable (using arithmetic operations)
  • Method 3: Without using a temporary variable (using XOR operation)

Question 8: Circular Swapping #

Write a C program that performs circular swapping of three variables. For example: if a=10, b=20, c=30, after swapping: a=30, b=10, c=20

Question 9: Assignment Chain #

What will be the final values of variables x, y, and z after executing the following code?

int x = 5, y = 10, z = 15;
x = y = z = 20;
x = x + y;
y = y - z;
z = x * y;

Conditional Statements #

Question 10: Even or Odd #

Write a C program that:

  • Takes an integer as input
  • Determines whether the number is even or odd
  • Displays the appropriate message

Question 11: Age Category #

Write a C program that categorizes a person based on their age:

  • Child (0-12 years)
  • Teenager (13-19 years)
  • Adult (20-59 years)
  • Senior Citizen (60+ years)
  • Handle invalid age inputs (negative numbers)

Question 12: Simple Calculator with Menu #

Write a C program that:

  • Displays a menu with arithmetic operations
  • Takes two numbers and an operation choice as input
  • Performs the selected operation using if-else statements
  • Displays the result

Nested Conditionals #

Question 13: Grade Calculator Enhancement #

Complete and improve the grade calculation program from main-1.c:

  • Fix any syntax errors in the provided code
  • Add validation for marks (0-100 range)
  • Add more detailed grade descriptions
  • Handle invalid input gracefully

Question 14: Triangle Classification #

Write a C program that:

  • Takes three sides of a triangle as input
  • First checks if the sides can form a valid triangle
  • If valid, classifies the triangle as:
    • Equilateral (all sides equal)
    • Isosceles (two sides equal)
    • Scalene (no sides equal)

Question 15: Quadratic Equation Solver #

Write a C program that solves quadratic equations (ax² + bx + c = 0):

  • Take coefficients a, b, c as input
  • Calculate discriminant (b² - 4ac)
  • Use nested if-else to determine:
    • Two distinct real roots (discriminant > 0)
    • One repeated real root (discriminant = 0)
    • No real roots (discriminant < 0)
  • Display appropriate messages for each case

Operator Precedence #

Question 16: Precedence Challenge 1 #

Without using a compiler, determine the output of the following expressions:

int a = 12, b = 4, c = 2;
printf("%d\n", a + b * c);
printf("%d\n", (a + b) * c);
printf("%d\n", a / b + c);
printf("%d\n", a % b * c);
printf("%d\n", a + b / c * a);

Question 17: Precedence Challenge 2 #

What will be the final value of x after executing each line?

int x = 10;
x = x + 5 * 2;        // x = ?
x = x * 2 + 3;        // x = ?
x = x / 4 + 1;        // x = ?
x = x % 3 + 2;        // x = ?

Question 18: Complex Expression #

Write a C program that evaluates the following mathematical expression: result = (a + b) × (c - d) / (e + f) + g % h

Where all variables are integers input by the user. Handle division by zero appropriately.

Comments and Code Documentation #

Question 19: Code Documentation #

Add appropriate single-line and multi-line comments to the following code:

#include <stdio.h>
int main() {
    int num1, num2, temp;
    printf("Enter two numbers: ");
    scanf("%d %d", &num1, &num2);
    if (num1 > num2) {
        temp = num1;
        num1 = num2;
        num2 = temp;
    }
    printf("Numbers in ascending order: %d %d\n", num1, num2);
    return 0;
}

Debugging Exercises #

Question 20: Find the Errors #

Identify and fix the errors in the following code snippets:

Code Snippet A:

#include <stdio.h>
int main() {
    int age;
    printf("Enter your age: ");
    scanf("%d" &age);
    if age >= 18
        printf("You are an adult");
    else
        printf("You are a minor");
    return 0;
}

Code Snippet B:

#include <stdio.h>
int main() {
    int marks = 85;
    if (marks >= 90 && marks <= 100)
        printf("Grade A");
    else if (marks >= 80)
        printf("Grade B");
    else if (marks >= 70)
        printf("Grade C");
    else if (marks >= 60)
        printf("Grade D");
    else
        printf("Grade F");
    // Missing return statement and braces for clarity
}

Challenge Problems #

Question 21: BMI Calculator #

Write a C program that:

  • Takes height (in meters) and weight (in kg) as input
  • Calculates BMI using the formula: BMI = weight / (height × height)
  • Categorizes BMI as:
    • Underweight (< 18.5)
    • Normal weight (18.5 - 24.9)
    • Overweight (25 - 29.9)
    • Obese (≥ 30)

Question 22: Electricity Bill Calculator #

Write a C program to calculate electricity bill based on the following rates:

  • First 100 units: ₹2 per unit
  • Next 200 units: ₹3 per unit
  • Above 300 units: ₹5 per unit
  • Add 10% tax on the total bill

Question 23: Number Properties Analyzer #

Write a C program that takes a 3-digit number and:

  • Checks if it’s a palindrome
  • Finds the sum of its digits
  • Determines if the sum is even or odd
  • Checks if the original number is divisible by the sum of its digits

Programming Best Practices #

Question 24: Code Improvement #

Rewrite the following code using better practices:

#include<stdio.h>
int main(){
int x,y;scanf("%d%d",&x,&y);
if(x>y)printf("x is greater");else printf("y is greater");
return 0;
}

Improve it by:

  • Adding proper spacing and indentation
  • Adding meaningful variable names
  • Adding comments
  • Handling the case where x equals y
  • Adding user-friendly prompts
Calendar August 27, 2025