C++ Booleans

The ISO/ANSI C++ Standard has added certain new data types to the original C++ specifications. They are provided to provide better control in certain situations as well as for providing conveniences to C++ programmers. A boolean data type is declared with the bool keyword and can only take the values in either true or false form. One of the new data types is bool.

Syntax: 

bool b1 = true;      // declaring a boolean variable with true value   

In C++, as mentioned earlier the data type bool has been introduced to hold a boolean value, true or false. The values true or false have been added as keywords in the C++ language. 

Important Points

1. The default numeric value of true is 1 and false is 0.

2. We can use bool-type variables or values true and false in mathematical expressions also. For instance,

int x = false + true + 6;

3. is valid and the expression on the right will evaluate to 7 as false has a value of 0 and true will have a value of 1.

4. It is also possible to convert implicitly the data type integers or floating point values to bool type. 

Example:

bool x = 0;  // false

bool y = 100;  // true

bool z = 15.75;  // true

The most common use of the bool datatype is for conditional statements. We can compare conditions with a boolean, and also return them telling if they are true or false.

Below is the C++ program to demonstrate bool data type: 

// C++ program to demonstrate 
// bool data type
#include <iostream>
using namespace std;

// Driver code
int main()
{
  int x1 = 10, x2 = 20, m = 2;
  bool b1, b2;
  
  // false
  b1 = x1 == x2; 

  // true
  b2 = x1 < x2; 

  cout << "Bool1 is = " << 
           b1 << "\n";
  cout << "Bool2 is = " << 
           b2 << "\n";
  bool b3 = true;

  if (b3)
    cout << "Yes" << "\n";
  else
    cout << "No" << "\n";

  int x3 = false + 5 * m - b3;
  cout << x3;

  return 0;
}

Bool1 is = 0
Bool2 is = 1
Yes
9