In the previous section we discussed the basics of C if – else Statements. Now let us take a look at some real-life application Problems.
1. Student Grade & Scholarship System
A university wants to automate its result processing system.
Write a C program to read the marks of five subjects for a student, calculate the average, and display the grade based on the following conditions:
Average >= 85 -> Grade A and Scholarship Eligible
Average >= 60 -> Grade B
Average >= 40 -> Grade C
Otherwise -> Fail
#include <stdio.h>
int main() {
int i, marks[5], sum = 0;
float avg;
for(i = 0; i < 5; i++) {
printf("Enter marks %d: ", i+1);
scanf("%d", &marks[i]);
sum += marks[i];
}
avg = sum / 5.0;
if (avg >= 85)
printf("Grade A - Scholarship Eligible");
else if (avg >= 60)
printf("Grade B");
else if (avg >= 40)
printf("Grade C");
else
printf("Fail");
return 0;
}
// Enter marks 1: 52
// Enter marks 2: 72
// Enter marks 3: 63
// Enter marks 4: 58
// Enter marks 5: 74
// Grade B
2. Bank Loan Eligibility System
A bank provides loans only to customers who satisfy certain conditions. Write a C program to check loan eligibility based on the following criteria:
- Their age must be between 24 and 65
- Should have a monthly salary of ₹25,000 or above
- Credit score must be 500 or more
Display whether the loan is approved or rejected along with the reason.
#include <stdio.h>
int main() {
int age, credit;
float salary;
printf("Enter age, salary, credit score: ");
scanf("%d %f %d", &age, &salary, &credit);
if (age >= 24 && age <= 65) {
if (salary >= 25000 && credit >= 500)
printf("Loan Approved");
else
printf("Loan Rejected: Financial Criteria Not Met");
} else {
printf("Loan Rejected: Age Criteria Not Met");
}
return 0;
}
// Enter age, salary, credit score: 25 20000 800
// Loan Rejected: Financial Criteria Not Met
3. Electricity Bill Calculator
An electricity board calculates the monthly bill based on unit consumption as follows:
- First 100 units -> ₹2 per unit
- Next 100 units -> ₹3 per unit
- Above 200 units -> ₹5 per unit
Write a C program to read the number of units consumed and calculate the total electricity bill.
#include <stdio.h>
int main() {
int units;
float bill;
printf("Enter units consumed: ");
scanf("%d", &units);
if (units <= 100)
bill = units * 2;
else if (units <= 200)
bill = 100 * 2 + (units - 100) * 3;
else
bill = 100 * 2 + 100 * 3 + (units - 200) * 5;
printf("Total Bill = %.2f", bill);
return 0;
}
// Enter units consumed: 155
// Total Bill = 365.00
4. Vehicle Insurance Premium System
An insurance company calculates vehicle insurance premiums based on the type of vehicle and age of the vehicle.
Vehicle Type:
- 1 -> Car
- 2 -> Bike
Premium rules vary based on whether the vehicle’s age is less than or equal to 5 years or more than 5 years.
Write a C program to display the insurance premium amount.
#include <stdio.h>
int main() {
int type, age;
printf("Enter vehicle type (1-Car, 2-Bike): ");
scanf("%d", &type);
printf("Enter vehicle age: ");
scanf("%d", &age);
if (type == 1) {
if (age <= 5)
printf("Premium: ₹5000");
else
printf("Premium: ₹8000");
} else if (type == 2) {
if (age <= 5)
printf("Premium: ₹2000");
else
printf("Premium: ₹4000");
} else {
printf("Invalid vehicle type");
}
return 0;
}
// Enter vehicle type (1-Car, 2-Bike): 1
// Enter vehicle age: 6
// Premium: ₹8000
5. Login System with Limited Attempts
Design a simple login authentication system in C.
The user is allowed a maximum of three attempts to enter the correct password.
- If the correct password is entered, display Login Successful
- If all three attempts fail, display Account Locked
Take the default password as 1234. It should only take numbers as inut.
#include <stdio.h>
int main() {
int password, attempts = 3;
while(attempts > 0) {
printf("Enter password: ");
if (scanf("%d", &password) != 1) {
printf("Invalid input! Numbers only.\n");
scanf("%*s");
continue;
}
if (password == 1234) {
printf("Login Successful\n");
return 0;
} else {
attempts--;
if (attempts > 0) {
printf("Wrong password. %d attempts left\n\n", attempts);
}
}
}
printf("Account Locked\n");
return 0;
}
// Enter password: 8520
// Wrong password. 2 attempts left
// Enter password: 6541
// Wrong password. 1 attempts left
// Enter password: 1234
// Login Successful
6. Hospital Patient Triage System
A hospital uses an automated triage system to assess patient condition.
Write a C program to classify a patient as:
- Critical if heart rate > 120 or oxygen level < 90
- Moderate if heart rate > 100
- Stable otherwise
The program should read heart rate and oxygen level and display the patient’s condition.
#include <stdio.h>
int main() {
int heartRate, oxygen;
printf("Enter heart rate and oxygen level: ");
scanf("%d %d", &heartRate, &oxygen);
if (heartRate > 120 || oxygen < 90)
printf("Critical Condition");
else if (heartRate > 100)
printf("Moderate Condition");
else
printf("Stable Condition");
return 0;
}
// Enter heart rate and oxygen level: 80 100
// Stable Condition
7. Online Shopping Cart Billing System
Question:
An online shopping platform provides discounts based on the total cart value.
- Total >= ₹10,000 -> 15% discount
- Total >= ₹5,000 -> 10% discount
Write a C program to read the number of items and price of each item, calculate the total amount, apply discount if applicable, and display the final payable amount.
#include <stdio.h>
int main() {
int items, i;
float price, total = 0;
printf("Enter number of items: ");
scanf("%d", &items);
for(i = 1; i <= items; i++) {
printf("Enter price of item %d: ", i);
scanf("%f", &price);
total += price;
}
if (total >= 10000)
total *= 0.85;
else if (total >= 5000)
total *= 0.90;
printf("Final Amount = %.2f", total);
return 0;
}
// Enter number of items: 5
// Enter price of item 1: 15
// Enter price of item 2: 50
// Enter price of item 3: 85
// Enter price of item 4: 120
// Enter price of item 5: 35
// Final Amount = 305.00
8. Traffic Violation Detection System
A traffic monitoring system checks for violations based on vehicle speed and helmet usage.
- Speed limit is 80 km/h
- Helmet status:
- 1 -> Worn
- 0 -> Not worn
Write a C program to detect and display the type of violation such as overspeeding, helmet violation, heavy fine or no violation.
#include <stdio.h>
int main() {
int speed, helmet;
printf("Enter speed and helmet status (1-Worn, 0-Not): ");
scanf("%d %d", &speed, &helmet);
if (speed > 80 && helmet == 0)
printf("Heavy Fine");
else if (speed > 80)
printf("Overspeeding Fine");
else if (helmet == 0)
printf("Helmet Violation");
else
printf("No Violation");
return 0;
}
// Enter speed and helmet status (1-Worn, 0-Not): 85
// 1
// Overspeeding Fine