C++ Boolean Expressions

Welcome to The Coding College! In this tutorial, we’ll dive into Boolean Expressions in C++, a fundamental concept for decision-making and control flow in programming. Boolean expressions evaluate to either true or false and are commonly used with comparison and logical operators.

What Are Boolean Expressions?

A Boolean Expression is an expression that evaluates to a Boolean value (true or false). They are widely used in:

  • Conditional statements (if, else, etc.).
  • Loops (while, for, etc.).
  • Logical operations.

Components of Boolean Expressions

  1. Comparison Operators
  2. Logical Operators
  3. Boolean Variables

1. Comparison Operators

Comparison operators compare two values and return a Boolean result.

OperatorDescriptionExampleResult
==Equal to5 == 5true
!=Not equal to5 != 3true
<Less than3 < 5true
>Greater than5 > 3true
<=Less than or equal to5 <= 5true
>=Greater than or equal to7 >= 8false

Example: Using Comparison Operators

#include <iostream>
using namespace std;

int main() {
    int a = 10, b = 20;

    cout << "a == b: " << (a == b) << endl;
    cout << "a != b: " << (a != b) << endl;
    cout << "a < b: " << (a < b) << endl;
    cout << "a > b: " << (a > b) << endl;

    return 0;
}

Output:

a == b: 0  
a != b: 1  
a < b: 1  
a > b: 0

2. Logical Operators

Logical operators combine Boolean expressions to create more complex conditions.

OperatorDescriptionExampleResult
&&Logical AND (all conditions true)(a > b) && (c < d)true
``Logical OR (at least one is true)
!Logical NOT (invert true/false)!(a > b)false

Example: Logical Operators in Action

#include <iostream>
using namespace std;

int main() {
    int x = 10, y = 20;

    cout << "x < y && x > 5: " << ((x < y) && (x > 5)) << endl;
    cout << "x > y || y > 15: " << ((x > y) || (y > 15)) << endl;
    cout << "!(x < y): " << !(x < y) << endl;

    return 0;
}

Output:

x < y && x > 5: 1  
x > y || y > 15: 1  
!(x < y): 0

3. Boolean Variables

Boolean expressions can involve Boolean variables, which store true or false.

#include <iostream>
using namespace std;

int main() {
    bool isHot = true;
    bool isSunny = false;

    cout << "Is it hot and sunny? " << (isHot && isSunny) << endl;
    cout << "Is it hot or sunny? " << (isHot || isSunny) << endl;
    cout << "Is it not sunny? " << (!isSunny) << endl;

    return 0;
}

Output:

Is it hot and sunny? 0  
Is it hot or sunny? 1  
Is it not sunny? 1

Boolean Expressions in Conditional Statements

Boolean expressions are commonly used in if, else, and else if statements to control program flow.

Example:

#include <iostream>
using namespace std;

int main() {
    int score = 85;

    if (score >= 90) {
        cout << "Grade: A" << endl;
    } else if (score >= 75) {
        cout << "Grade: B" << endl;
    } else {
        cout << "Grade: C" << endl;
    }

    return 0;
}

Output:

Grade: B

Boolean Expressions in Loops

Boolean expressions are used to control the execution of loops.

Example: while Loop

#include <iostream>
using namespace std;

int main() {
    int count = 0;

    while (count < 5) {
        cout << "Count: " << count << endl;
        count++;
    }

    return 0;
}

Output:

Count: 0  
Count: 1  
Count: 2  
Count: 3  
Count: 4

Example: for Loop

#include <iostream>
using namespace std;

int main() {
    for (int i = 0; i < 5; i++) {
        if (i % 2 == 0) {
            cout << i << " is even." << endl;
        } else {
            cout << i << " is odd." << endl;
        }
    }

    return 0;
}

Output:

0 is even.  
1 is odd.  
2 is even.  
3 is odd.  
4 is even.

Boolean Expressions with Functions

Boolean expressions can be returned from functions to encapsulate logic.

Example:

#include <iostream>
using namespace std;

bool isEven(int number) {
    return number % 2 == 0;
}

int main() {
    int num = 10;

    if (isEven(num)) {
        cout << num << " is even." << endl;
    } else {
        cout << num << " is odd." << endl;
    }

    return 0;
}

Output:

10 is even.

Summary

  • Boolean expressions are critical for decision-making and control flow in C++.
  • Combine comparison and logical operators to build complex expressions.
  • Use them in conditional statements, loops, and functions for dynamic programming.

Explore More at The Coding College

Visit The Coding College to learn more about Boolean expressions, control structures, and advanced C++ concepts.

What’s Next?

  • Learn about Boolean functions and recursion.
  • Explore error handling with Boolean checks.
  • Dive into advanced logical operations in algorithms.

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