In programming languages, we have various data types to store different types of data. Some of the most used data types are integer, string, float, and boolean. The boolean data type is a type of data that stores only two types of values i.e. True or False. These values are not case-sensitive depending upon programming languages. The name Boolean comes from the branch of mathematics called Boolean algebra, named after George Bool the mathematician.
What is Boolean Data Type?
The boolean data type is used to store logic values i.e. truth values which are true or false. It takes only 1 byte of space to store logic values. Here, true means 1, and false means 0. In the boolean data type any value other than ‘0’ is considered as ‘true’. Boolean values are most commonly used in data structures to decide the flow of control of a program and decision statements.In programming languages, we have various data types to store different types of data. Some of the most used data types are integer, string, float, and boolean. The boolean data type is a type of data that stores only two types of values i.e. True or False. These values are not case-sensitive depending upon programming languages. The name Boolean comes from the branch of mathematics called Boolean algebra, named after George Bool the mathematician.
Example of Declaration of Boolean Data Type
Below are code examples of how to declare a boolean data type in different languages such as C, C++, Java, Python, and JavaScript.
C++
#include <iostream>
using namespace std;
int main() {
bool a = true;
bool b = false;
bool c = 'yes';
cout<<"a: "<<a<<endl;
cout<<"b: "<<b<<endl;
cout<<"c: "<<c<<endl;
return 0;
}
|
C
#include <stdio.h>
#include <stdbool.h>
int main() {
bool a = true;
bool b = false;
bool c = 5;
printf("a: %d\n", a);
printf("c: %d\n", b);
printf("c: %d", c);
return 0;
}
|
Java
import java.io.*;
class GFG {
public static void main (String[] args) {
boolean a = true;
boolean b = false;
System.out.println("a: "+a);
System.out.println("b: "+b);
}
}
|
Python3
a = True
b = False
print("a: ",a)
print("b: ",b)
|
Javascript
let a = true;
let b = false;
console.log(a);
console.log(b);
|
Difference Between Boolean and Other Data Types
In programming languages, there are three types of data which are Booleans, Text, and Numbers. It is important to understand the differences between them and some basics about them.
- Booleans: They are either true (1) or false (0) and take only 1 byte of space in memory. while other data types take 2 to 8 bytes depending on the machine.
- Numbers: Numbers can be negative, positive, and zero or decimal numbers. The data type used to store numbers such as short, int, and double can take 2 to 8 bytes of space in memory.
- Text: Text includes characters, alphabets, numbers, and a collection of them. Text can be of character or string type. The size of 1 character is 2 bytes.
Logical and Boolean Operators
In programming, boolean operators are logical operators(AND, OR, and NOT) that are symbols that allow you to combine or modify conditions to make logical evaluations. They are utilized to perform logical operations on boolean values (true or false). They are used to control the flow of a program.
There are three logical operators:
- Logical AND ( && ) Operator
- Logical OR ( || ) Operator
- Logical NOT ( ! ) Operator
1. Logical AND Operator ( && )
The logical AND operator (&&) is a binary operator that returns true only if both of its operands are true. Otherwise, if one of the operands is false then it returns false. Truth table for the AND operator is given below:
|
true
| true
| true
|
true
| false
| false
|
false
| true
| false
|
false
| false
| false
|
Syntax of Logical AND
expression1 && expression2
Example of Logical AND
Below is the implementation of the above method:
C++
#include <iostream>
using namespace std;
int main()
{
int age = 25;
bool isStudent = true;
if (age > 18 && isStudent) {
cout << "You are eligible for a student discount."
<< endl;
}
else {
cout << "You are not eligible for a student "
"discount."
<< endl;
}
return 0;
}
|
C
#include <stdio.h>
#include <stdbool.h>
int main() {
int age = 45;
bool isStudent = false;
if (age > 18 && isStudent) {
printf("You are eligible for a student discount.\n");
}
else {
printf("You are not eligible for a student discount");
}
return 0;
}
|
Java
import java.io.*;
class GFG {
public static void main (String[] args) {
int age = 23;
boolean isStudent = true;
if (age > 18 && isStudent) {
System.out.println("You are eligible for a student discount.\n");
}
else {
System.out.println("You are not eligible for a student discount");
}
}
}
|
Python3
age = 23
isStudent = True
if age > 18 and isStudent:
print("You are eligible for a student discount.")
else:
print("You are not eligible for a student discount")
|
Javascript
let age = 23;
let isStudent = true;
if (age > 18 && isStudent) {
console.log("You are eligible for a student discount.\n");
}
else {
console.log("You are not eligible for a student discount");
}
|
OutputYou are eligible for a student discount.
Explaination: In the code, we have used AND operator to check whether a person is eligible for a discount or not. So, we check if person’s age is greater than 18 and the person is a student. If a person’s age is greater then 18 and also a student the condition became true, the message “You are eligible for a student discount.” will be printed. Otherwise, the else statement is executed.
2. Logical OR Operator ( || )
The Logical OR operator ( || ) is a binary operator that returns true if at least one of its operands is true. False will be returned only if both the operends are false. Here’s the truth table for the OR operator:
|
true
| true
| true
|
true
| false
| true
|
false
| true
| true
|
false
| false
| false
|
Syntax of Logical OR
expression1 || expression2
Example of Logical OR
Below is the implementation of the above method:
C++
#include <iostream>
using namespace std;
int main()
{
int num = 7;
if (num <= 0 || num >= 10) {
cout
<< "The number is outside the range of 0 to 10."
<< endl;
}
else {
cout << "The number is between 0 to 10." << endl;
}
return 0;
}
|
C
#include <stdio.h>
int main() {
int num = 7;
if (num <= 0 || num >= 10) {
printf("The number is outside the range of 0 to 10.");
}
else {
printf("The number is between 0 to 10.");
}
return 0;
}
|
Java
import java.io.*;
class GFG {
public static void main (String[] args) {
int num = 7;
if (num <= 0 || num >= 10) {
System.out.println("The number is outside the range of 0 to 10.");
}
else {
System.out.println("The number is between 0 to 10.");
}
}
}
|
Python3
num = 7
if (num <= 0 or num >= 10):
print("The number is outside the range of 0 to 10.")
else:
print("The number is between 0 to 10.")
|
Javascript
let num = 7;
if (num <= 0 || num >= 10) {
console.log("The number is outside the range of 0 to 10.");
}
else {
console.log("The number is between 0 to 10.");
}
|
OutputThe number is between 0 to 10.
Explaination: In the code, the condition num < 0 || num > 10 checks whether the number is either less than equal to 0 or greater than equal to 10. If either of these conditions is true, the message “The number is outside the range of 0 to 10.” will be printed otherwise else statement is printed.
3. Logical NOT Operator ( ! )
The logical NOT operator ( ! ) is a unary operator that is used change the boolean value. It returns true if the condition is false, and false if the condition is true. Here’s the truth table for the NOT operator:
Syntax of Logical NOT
! expression
Example of Logical NOT
Below is the implementation of the above method:
C++
#include <iostream>
using namespace std;
int main()
{
bool isLoggedIn = false;
if (!isLoggedIn) {
cout << "Please log in to access this feature."
<< endl;
}
else {
cout << "Welcome to GeeksforGeeks!" << endl;
}
return 0;
}
|
C
#include <stdio.h>
#include <stdbool.h>
int main() {
bool isLoggedIn = false;
if (!isLoggedIn) {
printf("Please log in to access this feature.");
}
else {
printf("Welcome to GeeksforGeeks!");
}
return 0;
}
|
Java
import java.io.*;
class GFG {
public static void main (String[] args) {
boolean isLoggedIn = false;
if (!isLoggedIn) {
System.out.println("Please log in to access this feature.");
}
else {
System.out.println("Welcome to GeeksforGeeks!");
}
}
}
|
Python3
isLoggedIn = False;
if not(isLoggedIn):
print("Please log in to access this feature.")
else:
print("Welcome to GeeksforGeeks!")
|
Javascript
let isLoggedIn = false;
if (!isLoggedIn) {
console.log("Please log in to access this feature.");
}
else {
console.log("Welcome to GeeksforGeeks!");
}
|
OutputPlease log in to access this feature.
Explanation: In the code, the condition ‘!isLoggedIn’ checks whether the user is not logged in. If the condition is true (i.e., the user is not logged in), the message “Please log in to access this feature.” will be displayed otherwise else statement will be printed.
Relational and Boolean Operators
Relational operators are used to determine the relations between two values or expressions, and based on this comparison, it returns a boolean value (either true or false) as the result.
Syntax:
operand1 relational_operator operand2
expression1 relational_operator expression2
Types of Relational Operators
We have six relational operators which are explained below with examples.
|
>
| Greater than
| (a > b) If ‘a’ is greater than ‘b’ it gives true otherwise false.
|
<
| Less than
| (a < b) If ‘a’ is less than ‘b’ it gives true otherwise false.
|
>=
| Greater than equal to
| (a >= b) If ‘a’ is greater than or equal to ‘b’ it gives true otherwise false.
|
<=
| Less than equal to
| (a <= b) If ‘a’ is less than or equal to ‘b’ it gives true otherwise false.
|
==
| Equal to
| (a == b) If ‘a’ is equal to ‘b’ it gives true otherwise false.
|
!=
| Not equal to
| ( a != b) If ‘a’ is not equal to ‘b’ it gives true otherwise false.
|
Example of Relational and Boolean Operators
In the below code, we have defined two variables with some integer value and we have printed the boolean output by comparing them using relational operators. In the output, we get 1, 0, 0, 0, and 1 where 0 means false and 1 means true.
C++
#include <iostream>
using namespace std;
int main()
{
int a = 10;
int b = 6;
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;
}
|
C
#include <stdio.h>
int main() {
int a = 10;
int b = 6;
printf("a > b = %d\n", a > b);
printf("a < b = %d\n", a < b);
printf("a == b = %d\n", a == b);
printf("a != b = %d", a != b);
return 0;
}
|
Java
import java.io.*;
class GFG {
public static void main (String[] args) {
int a = 10;
int b = 6;
System.out.println("a > b = "+ (a>b));
System.out.println("a < b = "+ (a<b));
System.out.println("a == b = "+ (a==b));
System.out.println("a != b = "+ (a!=b));
}
}
|
Python3
a = 10;
b = 6;
print("a > b =", (a > b));
print("a < b =", (a < b));
print("a == b =", (a == b));
print("a != b =", (a != b));
|
Javascript
let a = 10;
let b = 6;
console.log("a > b =", a > b);
console.log("a < b =", a < b);
console.log("a == b =", a == b);
console.log("a != b =", a != b);
|
Outputa > b = 1
a < b = 0
a == b = 0
a != b = 1
Conclusion
The Boolean data type, with its two fundamental values of true and false, lies at the heart of logical operations and decision-making in programming. Its simplicity and versatility make it an indispensable tool for developers across various programming languages and paradigms. By understanding how to work with Boolean data types and their associated logical operators, programmers can create more efficient, reliable, and powerful applications that can respond intelligently to different situations and user inputs.
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