Boolean Data Type

Boolean (bool) is a data type that can take one of two values: true or false. Syntax:

bool


              1
            
bool alive = true;

They are mostly used in comparison operators. Those operators (==, !=, <, >, >=, <=) return bool.

Note

std::cout prints booleans as numbers, 1 if the boolean is true, and 0 if the boolean is false.

main


              123456789101112
            
#include <iostream>

int main()
{
    bool istrue = true;
    bool obv = (5 > 0);
    bool wrong = (2 * 2 == 5);
    
    std::cout << istrue << std::endl;
    std::cout << obv << std::endl;
    std::cout << wrong << std::endl;
}

You can also flip the value of a boolean using the ! operator:

main


              123456789
            
#include <iostream>

int main()
{
    bool istrue = true;
    
    std::cout << istrue << std::endl;
    std::cout << !istrue << std::endl;
}

And most frequently, they are used as conditions in if/while/... statements.

main


              123456789101112
            
#include <iostream>

int main()
{
    bool b = true;
    
    if (b)
      std::cout << "b is true" << std::endl;
      
    if (1 > 0)
      std::cout << "1 is greater than 0" << std::endl;
}

The size of a bool is 1 byte. Yes, it would fit in 1 bit of memory, but you can't store a variable of size less than 1 byte (8 bit).

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Thanks for your feedback!

Section 4. Chapter 1

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Course Content

C++ Data Types

Boolean Data Type

Boolean (bool) is a data type that can take one of two values: true or false. Syntax:

bool


              1
            
bool alive = true;

They are mostly used in comparison operators. Those operators (==, !=, <, >, >=, <=) return bool.

Note

std::cout prints booleans as numbers, 1 if the boolean is true, and 0 if the boolean is false.

main


              123456789101112
            
#include <iostream>

int main()
{
    bool istrue = true;
    bool obv = (5 > 0);
    bool wrong = (2 * 2 == 5);
    
    std::cout << istrue << std::endl;
    std::cout << obv << std::endl;
    std::cout << wrong << std::endl;
}

You can also flip the value of a boolean using the ! operator:

main


              123456789
            
#include <iostream>

int main()
{
    bool istrue = true;
    
    std::cout << istrue << std::endl;
    std::cout << !istrue << std::endl;
}

And most frequently, they are used as conditions in if/while/... statements.

main


              123456789101112
            
#include <iostream>

int main()
{
    bool b = true;
    
    if (b)
      std::cout << "b is true" << std::endl;
      
    if (1 > 0)
      std::cout << "1 is greater than 0" << std::endl;
}

The size of a bool is 1 byte. Yes, it would fit in 1 bit of memory, but you can't store a variable of size less than 1 byte (8 bit).

Everything was clear?

Thanks for your feedback!

Section 4. Chapter 1