Scenario-Based Coding Questions on If-else in C++

Explanation:

This program uses a simple if-else statement to determine the clothing suggestion based on the temperature input. The if statement checks if the temperature is greater than 25°C. If true, it suggests wearing a shirt. If the temperature is 25°C or below, the else statement suggests wearing a jacket.

• The program starts by asking the user to enter the current temperature in Celsius, which is stored in the temperature variable.
• The program checks if the temperature is greater than 25°C (temperature > 25).
  • If true, it suggests wearing a shirt by printing “Wear a shirt.”
• If the condition is not true, the else block executes and the program prints the message “Wear a jacket.”

#include <iostream>
using namespace std;

int main() {
int temperature;

// Prompting the user to input the current temperature
cout << "Enter the current temperature in °C: ";
cin >> temperature;

// Providing outfit suggestions based on the temperature
if (temperature > 25) {
cout << "Wear a shirt.\n";
} else {
cout << "Wear a jacket.\n";
}

return 0;
}

Explanation:

This program uses an if-else condition to check whether the user’s height meets the minimum requirement. If the height is 120 cm or more, the program allows the user to ride.

• The program begins by asking the user to input their height in centimeters, which is then stored in the height variable.
• The program checks if the height is greater than or equal to 120 cm using the condition (height >= 120).
• If the condition is true, it informs the user that they can ride the roller coaster by printing “You can ride the roller coaster!”
• If the condition is false (i.e., the height is less than 120 cm), the program prints “Sorry, you cannot ride the roller coaster.”
• The program thus determines eligibility for the ride based on the user’s height.

#include <iostream>
using namespace std;

int main() {
    int height;
    
    // Taking input from the user
    cout << "Enter your height (cm): ";
    cin >> height;
    
    // Decision-making based on height
    if (height >= 120) {
        cout << "You can ride the roller coaster!\n";
    } else {
        cout << "Sorry, you cannot ride the roller coaster.\n";
    }
    
    return 0;
}

Explanation:

The program asks the user for their age. It then checks if the age is 18 or above using an if-else condition. If true, the program tells the user they can watch the movie. Otherwise, it informs them that they are too young.

• The program starts by asking the user to enter their age, which is stored in the age variable.
• It then evaluates if the age is 18 or older using the condition (age >= 18).
• If the condition is true, the program outputs “You are old enough to watch this movie.”
• If the condition is false (i.e., the age is less than 18), the program outputs “You are too young to watch this movie.”
• This way, the program determines and communicates if the user meets the age requirement for watching the movie.

#include <iostream>
using namespace std;

int main() {
    int age;
    
    cout << "Enter your age: ";
    cin >> age;
    
    if (age >= 18) {
        cout << "You are old enough to watch this movie." << endl;
    } else {
        cout << "You are too young to watch this movie." << endl;
    }
    
    return 0;
}

Explanation:

This program uses an if-else statement to determine if the number of logged steps exceeds 1000. If so, it informs the user that they’ve earned a reward. If the steps are 1000 or fewer, no reward is given.

• The program begins by asking the user to enter the number of steps they’ve Jogged, which is stored in the steps variable.
• It then checks if the number of steps is greater than 1000 using the condition (steps > 1000).
• If the condition is true (i.e., the user logged more than 1000 steps), the program displays “Congratulations! You’ve earned a reward!”
• If the condition is false (i.e., the user logged 1000 or fewer steps), the program displays “Keep trying for a reward.”
• This approach helps the user know whether they have achieved the required number of steps to earn a reward.

#include <iostream>
using namespace std;

int main() {
    int steps; // Variable to store the number of steps logged

    // Prompting the user to enter the number of steps logged
    cout << "Enter the number of steps logged: ";
    cin >> steps;

    // Checking if the steps exceed 1000 to determine if a reward is earned
    if (steps > 1000) {
        cout << "Congratulations! You’ve earned a reward!\n";
    } else {
        cout << "Keep trying for a reward.\n";
    }

    return 0;
}

Explanation:

• The program starts by setting up the correct admin username and password. Think of these as the “key” to enter the admin portal.
• Next, it asks the user to enter their username and password. These are compared with the stored correct credentials.
• The program checks both the username and password together. Only if both are correct will the system grant access.
• If either the username or password is wrong, the system will block access and show a warning message.
• In short, it teaches how to use multiple conditions in decision-making to allow or block access in actual login systems.

#include <iostream>
#include <string>
using namespace std;

int main() {
    // Predefined admin credentials 
    string adminUsername = "admin";
    string adminPassword = "admin54321#";

    // Variables to store user input
    string enteredUsername, enteredPassword;

    // Prompt user to enter login details
    cout << "Enter username: ";
    cin >> enteredUsername;

    cout << "Enter password: ";
    cin >> enteredPassword;

    // Check if both username and password match
    if (enteredUsername == adminUsername && enteredPassword == adminPassword) {
        cout << "Welcome to Syntax Scenarios Admin Portal" << endl;
    } else {
        cout << "Access denied. Invalid credentials" << endl;
    }

    return 0;
}

Explanation:

The program reads the volume of coffee as input and utilizes if-else if-else statements to determine and print the suitable coffee size based on the provided volume because in this situation out of all conditons only one can be true.

• The program starts by asking the user to input the coffee volume in milliliters, which is stored in the volume variable.
• It then uses a series of if-else if-else statements to determine the appropriate coffee size based on the volume:
  • If the volume is greater than 350 ml, the program outputs “Large.”
  • If the volume is between 200 ml and 350 ml (inclusive), it outputs “Medium.”
  • If the volume is less than 200 ml, it outputs “Small.”
• This helps the user decide on the coffee size based on the amount of coffee they have.

#include <iostream>
using namespace std;

int main() {
    double volume;
    
    // Asking the user to input the coffee volume
    cout << "Enter the coffee volume in milliliters (ml): ";
    cin >> volume;
    
    // Recommending the coffee size based on the volume
    if (volume > 350) {
        cout << "Large" << endl;
    } else if (volume >= 200) {
        cout << "Medium" << endl;
    } else {
        cout << "Small" << endl;
    }
    
    return 0;
}

Explanation:

• The program first asks the user to type the traffic signal color. It then checks the input one by one:
  • If it matches "Red", the program prints Stop.
  • If it matches "Yellow", it prints Wait.
  • If it matches "Green", it prints Go.
  • If the input doesn’t match any valid color, the program prints Invalid signal.
• This way, the program ensures that it displays the correct action based on the traffic signal.

#include <iostream>
#include <string>
using namespace std;

int main() {
    string signal;

    // Prompt the user to enter the traffic signal color
    cout << "Enter traffic signal color (Red, Yellow, Green): ";
    cin >> signal;

    // Check the input and display the correct action
    if (signal == "Red" || signal == "red") {
        cout << "Stop" << endl;
    } 
    else if (signal == "Yellow" || signal == "yellow") {
        cout << "Wait" << endl;
    } 
    else if (signal == "Green" || signal == "green") {
        cout << "Go" << endl;
    } 
    else {
        cout << "Invalid signal" << endl;
    }

    return 0;
}

Explanation:

The program will ask the user for the total purchase amount. Using an if-else condition, it checks if the amount is $50 or more. If true, it confirms that the user is eligible for a discount; otherwise, it informs them that they are not eligible.

• The program begins by asking the user to input their total purchase amount, which is stored in the purchaseAmount variable.
• It then uses an if-else condition to check if the total amount is $50 or more:
  • If the amount is $50 or more, the program outputs “You are eligible for a discount!”
  • If the amount is less than $50, the program outputs “You are not eligible for a discount.”
• This helps the user determine if they qualify for a store discount based on their purchase amount.

#include <iostream>
using namespace std;

int main() {
    float purchaseAmount;
    
    cout << "Enter the total purchase amount: $";
    cin >> purchaseAmount;
    
    if (purchaseAmount >= 50) {
        cout << "You are eligible for a discount!" << endl;
    } else {
        cout << "You are not eligible for a discount." << endl;
    }
    
    return 0;
}

Explanation:

The program calculates the cost of renting a car based on the number of days rented, using different rates depending on the rental duration:

• The program begins by asking the user for the number of days they rented the car, which is stored in the days variable.
• It then calculates the total cost based on the rental duration using different rates:
  • For up to 3 days: The cost is calculated at $50 per day.
  • For days 4 through 7: The cost is $40 per day for these days.
  • For more than 7 days: The cost is $30 per day for the days beyond 7, with the previous rates applied to the initial days.

#include <iostream>
using namespace std;

int main() {
    int days;
    double cost = 0.0;
    
    // Prompt the user to enter the number of rental days
    cout << "Enter the number of days rented: ";
    cin >> days;
    
    // Calculate total rental cost based on days rented
    if (days <= 3) {
        cost = days * 50.0;
    } else if (days <= 7) {
        cost = 3 * 50.0 + (days - 3) * 40.0;
    } else {
        cost = 3 * 50.0 + 4 * 40.0 + (days - 7) * 30.0;
    }
    
    // Output the total rental cost
    cout << "Total rental cost: $" << cost << endl;
    
    return 0;
}

Explanation:

The program calculates the utility bill based on the number of units consumed. It uses if-else statements to apply different rates depending on the total units:

• The program starts by asking the user for the number of units consumed, which is stored in the units variable.
• It then calculates the total utility bill based on the number of units, using different rates for different ranges:
  • For up to 100 units: The bill is calculated at $0.50 per unit and the first if block will be executed.
  • For units between 101 and 200: The cost is $50 for the first 100 units plus $0.75 per unit for the additional units from 101 to 200. So, the else-if condition will be executed.
  • For units above 200: The cost includes $50 for the first 100 units, $75 for the next 100 units, plus $1.00 per unit for any units beyond 200. In this case the else block will execute because both the previous conditions were false.

#include <iostream>
using namespace std;

int main() {
    int units;
    double totalBill = 0.0;
    
    cout << "Enter the number of units consumed: ";
    cin >> units;
    
    if (units <= 100) {
        totalBill = units * 0.50;
    } else if (units <= 200) {
        totalBill = 100 * 0.50 + (units - 100) * 0.75;
    } else {
        totalBill = 100 * 0.50 + 100 * 0.75 + (units - 200) * 1.00;
    }
    
    cout << "Total utility bill: $" << totalBill << endl;
    
    return 0;
}

Explanation

• The program first asks the user to enter three pieces of information: heart rate, oxygen level, and age.
• It validates each input to ensure it is a positive number. If not, it shows an error and stops.
• Then, it checks if the patient is Critical.
  • If the heart rate is above 120 or oxygen level is below 90%, the patient is marked as Critical.
• Else if the patient is not Critical, it checks for High Priority.
  • The patient is High Priority if they are older than 60 and their heart rate is in a safe range (100–120) and oxygen level is normal (90 or above).
• Then, if neither Critical nor High Priority conditions are met, the patient is marked as Normal.
• This way, the most urgent cases are handled first, and the program uses combined conditions (|| and &&) and ordered checks to decide correctly.

#include <iostream>
using namespace std;

int main() {
    int heartRate, oxygen, age;

    // Taking input from the user
    cout << "Enter heart rate (bpm): ";
    cin >> heartRate;
    if (heartRate <= 0) {
        cout << "Invalid input! Heart rate must be a positive number." << endl;
        return 0;
    }


    cout << "Enter oxygen level (%): ";
    cin >> oxygen;
    if (oxygen <= 0) {
        cout << "Invalid input! Oxygen level must be a positive number." << endl;
        return 0;
    }
   

    cout << "Enter age (years): ";
    cin >> age;
    if (age <= 0) {
        cout << "Invalid input! Age must be a positive number." << endl;
        return 0;
    }

    // Checking patient priority step by step
    if (heartRate > 120 || oxygen < 90) {
        // Critical condition
        cout << "Critical" << endl;
    } else if (age > 60 && heartRate >= 100 && heartRate <= 120 && oxygen >= 90) {
        // High priority condition
        cout << "High Priority" << endl;
    } else {
        // Normal condition
        cout << "Normal" << endl;
    }

    return 0;
}

Explanation:

• The program asks the student to enter the hour, minute, and whether it’s AM or PM separately.
• The first check is whether the time is in the PM hours. If it is, the student is automatically marked Absent because the class only happens in the morning.
• If it’s AM, the program then looks at the specific morning ranges to decide attendance:
  • If the student joins between 9:00 and 9:15 AM, they are Present.
  • If the student joins after 9:15 but before 10:00 AM, they are Late.
  • Any time from 10:00 AM onwards is considered Absent.
• The order of checks matters: PM is checked first, then the exact hour and minute ranges.
• By combining the hour and minute conditions logically, the program can accurately assign attendance.

#include <iostream>
using namespace std;

int main() {
    int hour, minute;
    char ampm;

    // Input hour, minute, and AM/PM separately
    cout << "Enter hour: ";
    cin >> hour;
    cout << "Enter minute: ";
    cin >> minute;
    cout << "Enter AM/PM (A/P): ";
    cin >> ampm;

    // Check PM first
    if (ampm == 'PM' || ampm == 'pM' || ampm == 'pm') {
        cout << "Absent" << endl;
    } 
    // Present: 9:00–9:15 AM
    else if (hour == 9 && minute <= 15) {
        cout << "Present" << endl;
    } 
    // Late: 9:16–9:59 AM
    else if (hour == 9 && minute > 15) {
        cout << "Late" << endl;
    } 
    // Any other time is absent
    else {
        cout << "Absent" << endl;
    }

    return 0;
}

Explanation:

• The program first stores blacklisted IPs, safe IPs, and passcodes in separate variables. This is done so we can easily compare the user’s input with known values.
• The user is asked to enter their device IP and file passcode. Reading input as strings allows us to check exact matches for IPs and passcodes.
• Then the first check is whether the IP is blacklisted. This step is done first because blacklisted IPs are high-risk and must be denied immediately for security.
• Next, the program checks if the IP is a safe authorized device. We do this after the blacklist check to only grant access to trusted devices. If the IP is safe, the program then checks the passcode:
  • If the passcode matches the top-secret code, access is granted for top-secret files. We do this to ensure only users with correct credentials get sensitive data.
  • If the passcode matches the confidential code, access is granted for confidential files. This allows users with lower-level access to still retrieve permitted data.
  • If the passcode is wrong, it is flagged as an unauthorized access attempt. This step helps log or alert for potential security breaches.
  • If the IP is neither blacklisted nor safe, the system blocks access and treats the device as unknown. This prevents unknown devices from entering the system.
• Logical operators used:
  • || (OR) is used to check multiple IPs in one step. This reduces repeated checks and makes the code cleaner.
  • && (AND) is used to ensure both IP and passcode are correct before granting access. This prevents partial matches from granting access.
  • == is used to compare strings exactly because IPs and passcodes must match perfectly.
• This setup uses a careful order of evaluation and combined conditions to handle all realistic scenarios.

#include <iostream>
#include <string>
using namespace std;

int main() {
    string ip, passcode;

    // Blacklisted IPs
    string blacklist1 = "10.0.0.5";
    string blacklist2 = "172.16.0.2";
    string blacklist3 = "192.168.1.50";

    // Safe IPs
    string safe1 = "192.168.0.101";
    string safe2 = "192.168.0.102";

    // Passcodes
    string topSecret = "Intel2026";
    string confidential = "Intel2025";

    cout << "Enter your device IP: ";
    cin >> ip;

    cout << "Enter file passcode: ";
    cin >> passcode;

    // Flat if-else checks
    if (ip == blacklist1 || ip == blacklist2 || ip == blacklist3) {
        cout << "Access Denied: Blacklisted IP";
    } 
    else if ((ip == safe1 || ip == safe2) && passcode == topSecret) {
        cout << "Access Granted: Top-secret Files Retrieved";
    } 
    else if ((ip == safe1 || ip == safe2) && passcode == confidential) {
        cout << "Access Granted: Confidential Files Retrieved";
    } 
    else if (ip == safe1 || ip == safe2) {
        cout << "Unauthorized Access Attempt";
    } 
    else {
        cout << "Access Blocked: Unknown Device";
    }

    return 0;
}

Explanation:

The program takes the user’s speed as input. It first checks if the speed is within the limit (60 km/h). If true, it tells the user they are safe. If false, it checks how much the limit is exceeded by. If the excess is 10 km/h or less, it issues a warning. If the excess is more than 10 km/h, it issues a ticket.

• The program starts by asking the user to enter their driving speed, which is stored in the speed variable.
• It then uses conditional checks to determine the appropriate response based on the speed:
  • If the speed is 60 km/h or less: The first if statememt will execute and program indicates that the user is driving safely.
  • If the speed is between 61 km/h and 70 km/h (exceeding the limit by up to 10 km/h): The second condition will execute and program issues a warning to slow down.
  • If the speed is more than 70 km/h (exceeding the limit by more than 10 km/h): The else block will execute and program notifies the user that they are speeding and will receive a ticket.

#include <iostream>
using namespace std;

int main() {
    int speed;
    
    cout << "Enter your driving speed (km/h): ";
    cin >> speed;
    
    if (speed <= 60) {
        cout << "You are driving safely." << endl;
    } else if (speed <= 70) {
        cout << "Warning! Slow down." << endl;
    } else {
        cout << "You are speeding! You will receive a ticket." << endl;
    }
    
    return 0;
}