Logical Operators in C++
Logical operators in C++ are used to combine two or more conditions. These operators help the program decide whether a final result is true (1) or false (0).
These operators are mostly used in decision-making statements like
if, else-if, while, and loops.
Types of Logical Operators
C++ provides the following logical operators:
| Operator | Name | Meaning | Example |
|---|---|---|---|
&& |
Logical AND | True only if both conditions are true | (5 > 2) && (8 > 3) → true |
|| |
Logical OR | True if any one condition is true | (4 > 9) || (10 > 3) → true |
! |
Logical NOT | Reverses the condition (true → false) | !(5 == 5) → false |
Explanation of Logical Operator
1. Logical AND (&&)
The Logical AND operator returns true only when both conditions are true. If any one condition is false, the result becomes false.
- Used when multiple conditions must be true together.
- Common in range checks (e.g., age >= 18 && age <= 60).
Examples:
(10 > 5) && (20 > 15) → true
(10 > 5) && (20 < 15) → false2. Logical OR (||)
The Logical OR operator returns true if any one of the conditions is true. It becomes false only when both conditions are false.
- Used when at least one condition is enough to make the result true.
- Helpful in permission checks (e.g., admin || teacher).
Examples:
(5 > 10) || (20 > 15) → true
(5 > 10) || (20 < 15) → false3. Logical NOT (!)
The Logical NOT operator reverses the condition. It converts true → false and false → true.
- Used to check the opposite of a condition.
- Helpful in validation (e.g., !loggedIn).
Examples:
!(5 == 5) → false
!(5 > 10) → trueExample: Using All Logical Operators
Let us use all logical operators in a C++ program:
#include <iostream>
using namespace std;
int main() {
int a = 10;
int b = 20;
cout << "Result of (a > 5) && (b > 15) : " << ((a > 5) && (b > 15)) << endl;
cout << "Result of (a > 15) || (b > 15) : " << ((a > 15) || (b > 15)) << endl;
cout << "Result of !(a == b) : " << (!(a == b)) << endl;
return 0;
}
Output:
Result of (a > 5) && (b > 15) : 1
Result of (a > 15) || (b > 15) : 1
Result of !(a == b) : 1
Explanation
- (a > 5) && (b > 15) → 10 > 5 and 20 > 15 → both conditions are true → result = 1.
- (a > 15) || (b > 15) → 10 > 15 is false but 20 > 15 is true → one condition is true → result = 1.
- !(a == b) → (10 == 20) is false → NOT false becomes true → result = 1.
Using Logical Operators in if Statements
Logical operators allow us to check multiple conditions in a single
if statement. They help the program take decisions based
on more than one condition.
Checking Age Eligibility for a Job
// C++ Program to check job eligibility
#include <iostream>
using namespace std;
int main() {
int age = 25;
if (age >= 18 && age <= 30) {
cout << "Eligible for the job";
}
else {
cout << "Not eligible for the job";
}
return 0;
}Output:
Eligible for the job
Explanation
- The job requires age between 18 and 30.
- Here age = 25.
- Both conditions are true: 25 ≥ 18 and 25 ≤ 30.
- So true && true = true, therefore the if block runs.
Summary:
- Logical operators help combine multiple conditions.
- They return either 1 (true) or 0 (false).
- C++ provides three logical operators: AND, OR, NOT.
- Mostly used in if-else conditions and loops.