Session 7: Advanced Conditions and Nested Logic

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January 7, 2025 - 6 minutes read - 1249 words

Session 7: Advanced Conditions and Nested Logic

Weekday Session 1 hour Phase 2: Control Structures

Create more sophisticated decision-making with nested conditions, logical operators, and switch statements for cleaner code.

🎯 Key Skills You'll Learn:

Nested if statements
Complex logical conditions
Switch statements
Ternary operator

🚀 Session Project:

Smart Calculator with Error Checking

Learning Objectives

Learn about nested if statements
Understand complex logical conditions
Practice combining multiple conditions
Create more sophisticated decision-making programs

Warm-up (5 minutes)

Modify your Rock, Paper, Scissors game from last session. What would you need to change to make the computer pick a random choice instead of always the same one?

New Concept Introduction (20 minutes)

Nested If Statements

Sometimes you need to check one condition inside another:

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#include <iostream>
using namespace std;

int main() {
    int age;
    bool hasLicense;
    
    cout << "Enter your age: ";
    cin >> age;
    cout << "Do you have a driver's license? (1 for yes, 0 for no): ";
    cin >> hasLicense;
    
    if (age >= 16) {
        if (hasLicense) {
            cout << "You can drive!" << endl;
        } else {
            cout << "You're old enough, but need a license." << endl;
        }
    } else {
        cout << "You're too young to drive." << endl;
    }
    
    return 0;
}

Complex Logical Conditions

You can combine multiple conditions in one if statement:

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// Using AND (&&)
if (age >= 16 && hasLicense) {
    cout << "You can drive!" << endl;
}

// Using OR (||)
if (grade == 'A' || grade == 'B') {
    cout << "Great job!" << endl;
}

// Combining AND and OR (use parentheses for clarity)
if ((age >= 16 && hasLicense) || (age >= 18)) {
    cout << "You have driving privileges!" << endl;
}

Switch Statements

For checking many specific values, switch can be cleaner than multiple if-else:

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#include <iostream>
using namespace std;

int main() {
    char grade;
    cout << "Enter your letter grade: ";
    cin >> grade;
    
    switch (grade) {
        case 'A':
            cout << "Excellent!" << endl;
            break;
        case 'B':
            cout << "Good job!" << endl;
            break;
        case 'C':
            cout << "Average" << endl;
            break;
        case 'D':
            cout << "Below average" << endl;
            break;
        case 'F':
            cout << "Failing" << endl;
            break;
        default:
            cout << "Invalid grade" << endl;
    }
    
    return 0;
}

Important: Don’t forget the break; statements!

Conditional Operator (Ternary)

A shortcut for simple if-else:

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// Long way
string message;
if (age >= 18) {
    message = "Adult";
} else {
    message = "Minor";
}

// Short way (ternary operator)
string message = (age >= 18) ? "Adult" : "Minor";

Hands-on Practice (25 minutes)

Exercise 1: Enhanced Grade Calculator (10 minutes)

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#include <iostream>
using namespace std;

int main() {
    double score;
    bool extraCredit;
    
    cout << "Enter your test score: ";
    cin >> score;
    cout << "Did you do extra credit? (1 for yes, 0 for no): ";
    cin >> extraCredit;
    
    // Add 5 points for extra credit
    if (extraCredit) {
        score += 5;
        cout << "Extra credit added! New score: " << score << endl;
    }
    
    // Determine grade
    if (score >= 97) {
        cout << "Grade: A+" << endl;
    } else if (score >= 93) {
        cout << "Grade: A" << endl;
    } else if (score >= 90) {
        cout << "Grade: A-" << endl;
    } else if (score >= 87) {
        cout << "Grade: B+" << endl;
    } else if (score >= 83) {
        cout << "Grade: B" << endl;
    } else if (score >= 80) {
        cout << "Grade: B-" << endl;
    } else if (score >= 70) {
        cout << "Grade: C" << endl;
    } else if (score >= 60) {
        cout << "Grade: D" << endl;
    } else {
        cout << "Grade: F" << endl;
    }
    
    return 0;
}

Exercise 2: Movie Rating System (15 minutes)

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#include <iostream>
using namespace std;

int main() {
    int age;
    char rating;
    bool withParent;
    
    cout << "Enter your age: ";
    cin >> age;
    cout << "Enter movie rating (G, P, M, R): ";
    cin >> rating;
    
    switch (rating) {
        case 'G':
            cout << "Anyone can watch this movie!" << endl;
            break;
            
        case 'P':
            if (age >= 13) {
                cout << "You can watch this movie!" << endl;
            } else {
                cout << "Do you have a parent with you? (1 for yes, 0 for no): ";
                cin >> withParent;
                if (withParent) {
                    cout << "You can watch with parental guidance!" << endl;
                } else {
                    cout << "Sorry, you need a parent to watch this movie." << endl;
                }
            }
            break;
            
        case 'M':
            if (age >= 15) {
                cout << "You can watch this movie!" << endl;
            } else {
                cout << "Sorry, you must be 15 or older." << endl;
            }
            break;
            
        case 'R':
            if (age >= 18) {
                cout << "You can watch this movie!" << endl;
            } else {
                cout << "Sorry, you must be 18 or older." << endl;
            }
            break;
            
        default:
            cout << "Invalid rating entered." << endl;
    }
    
    return 0;
}

Challenge/Quiz (10 minutes)

Challenge: Smart Calculator Create a calculator that:

Asks for two numbers
Asks for an operation (+, -, *, /)
Performs the calculation
Has these smart features:
- Prevents division by zero
- For negative results, asks if user wants the absolute value
- For division, warns if the result will have a remainder
- Asks if user wants to do another calculation

Use nested if statements and logical operators appropriately.

Validation Prompt

🤖 AI Validation Prompt

Copy this prompt and your code to ChatGPT or Claude for instant feedback:


```
I'm learning C++ and just completed Session 7. Here's my solution to the Smart Calculator challenge:

[PASTE YOUR CODE HERE]

The challenge was: Create a smart calculator with error checking, user options, and helpful warnings.

Please check if my solution:
1. Uses nested if statements appropriately
2. Prevents division by zero
3. Uses switch statement or if-else for operations
4. Implements the smart features correctly
5. Has clear user interaction and error messages

If there are issues, please explain what's wrong and give me a hint to fix it (don't give me the complete solution).
```

What You Learned

✅ Nested if statements for complex logic
✅ Combining conditions with && and ||
✅ Switch statements for multiple specific values
✅ Ternary operator for simple conditions
✅ Error checking and input validation

Next Session Preview

In Session 8, you’ll learn about loops - how to make your programs repeat actions automatically!