Course Content
C# Basics
C# Basics
Logical Operators
Logical Operators can be used for combining two logical expressions or logical values. Following are the three logical operators:
Operator | Operation |
&& | AND |
|| | OR |
! | NOT |
Note
An operand refers to a value or expression that is used as an input for an operator in a statement or expression. For-example in the expression
1 + 2
, the values1
and2
are operands. In the case of logical operators, an operand is always a boolean expression or value.
The AND (&&
) operator takes two operands and returns true
only if both the operands are true
. It is demonstrated by the following code:
main
using System; namespace ConsoleApp { internal class Program { static void Main(string[] args) { Console.WriteLine(true && true); // Output: True Console.WriteLine(true && false); // Output: False Console.WriteLine(false && true); // Output: False Console.WriteLine(false && false); // Output: False } } }
Instead of directly using the true
and false
literals (values), we commonly use expressions:
main
using System; namespace ConsoleApp { internal class Program { static void Main(string[] args) { /* A program to check if the variable `value` is in the range specified by `range_start` and `range_end` variables.*/ int value = 7; int range_start = 0; int range_end = 10; Console.WriteLine(range_start < value && value < range_end); // Output: True } } }
The OR (||
) operator returns true
if any one of the operands is true
:
main
using System; namespace ConsoleApp { internal class Program { static void Main(string[] args) { Console.WriteLine(true || true); // Output: True Console.WriteLine(true || false); // Output: True Console.WriteLine(false || true); // Output: True Console.WriteLine(false || false); // Output: False } } }
Following is an example which uses the OR (||
) operator:
main
using System; namespace ConsoleApp { internal class Program { static void Main(string[] args) { int val1 = 5; int val2 = 7; int val3 = 9; Console.WriteLine(val2 > val1 || val2 > val3); // Output: True } } }
The NOT (!) operator simply negates (inverts) the logical expression or logical value. So if an expression returns true
, it changes it into false
.
main
using System; namespace ConsoleApp { internal class Program { static void Main(string[] args) { Console.WriteLine(!true); // Output: False Console.WriteLine(!false); // Output: True // We need to enclose expressions in brackets () before negating them Console.WriteLine(!(5 < 0)); // Output: True Console.WriteLine(!(0 < 5 && 5 < 10)); // Output: False } } }
Everything was clear?