Logical Operators

In PHP, logical operators are used to combine conditional statements. These operators allow you to create more complex conditions by combining multiple conditions together.

Logical operators are generally used in conditional statements such as if, while, and for loops to control the flow of program execution based on specific conditions.

The following table highlights the logical operators that are supported by PHP.

Assume variable $a holds 10 and variable $b holds 20, then −

Operator	Description	Example
and	Called Logical AND operator. If both the operands are true then condition becomes true.	(A and B) is true
or	Called Logical OR Operator. If any of the two operands are non zero then condition becomes true.	(A or B) is true
&&	Called Logical AND operator. The AND operator returns true if both the left and right operands are true.	(A && B) is true
||	Called Logical OR Operator. If any of the two operands are non zero then condition becomes true.	(A || B) is true
!	Called Logical NOT Operator. Use to reverses the logical state of its operand. If a condition is true then Logical NOT operator will make false.	!(A && B) is false

Basic Usage of Logical Operators

The following example shows how you can use these logical operators in PHP −

<?php
   $a = 42;
   $b = 0;

   if ($a && $b) {
  echo "TEST1 : Both a and b are true \n";
   } else {
  echo "TEST1 : Either a or b is false \n";
   }

   if ($a and $b) {
  echo "TEST2 : Both a and b are true \n";
   } else {
  echo "TEST2 : Either a or b is false \n";
   }

   if ($a || $b) {
  echo "TEST3 : Either a or b is true \n";
   } else {
  echo "TEST3 : Both a and b are false \n";
   }

   if ($a or $b) {
  echo "TEST4 : Either a or b is true \n";
   } else {
  echo "TEST4 : Both a and b are false \n";
   }

   $a = 10;
   $b = 20;

   if ($a) {
  echo "TEST5 : a is true \n";
   } else {
  echo "TEST5 : a is false \n";
   }

   if ($b) {
  echo "TEST6 : b is true \n";
   } else {
  echo "TEST6 : b is false \n";
   }

   if (!$a) {
  echo "TEST7 : a is true \n";
   } else {
  echo "TEST7 : a is false \n";
   }

   if (!$b) {
  echo "TEST8 : b is true \n";
   } else {
  echo "TEST8 : b is false";
   }
?>

Output

It will produce the following output −

TEST1 : Either a or b is false 
TEST2 : Either a or b is false 
TEST3 : Either a or b is true 
TEST4 : Either a or b is true 
TEST5 : a is true 
TEST6 : b is true 
TEST7 : a is false 
TEST8 : b is false

Using AND (&&) and OR (||) with User Input

In the below PHP code example we will check if a user is eligible for a discount as per the age and membership status.

<?php
   $age = 25;
   $isMember = true;

   if ($age > 18 && $isMember) {
  echo "You are eligible for a discount!\n";
   } else {
  echo "Sorry, you are not eligible for a discount.\n";
   }

   if ($age < 18 || !$isMember) {
  echo "You need to be at least 18 years old or a member to get a discount.";
   }
?>

Output

This will generate the below output −

You are eligible for a discount!

Check Multiple Conditions with And and Or

Now the below code we will shows that the And and Or keywords work similarly like && and ||, but with lower precedence.

<?php
   $x = 10;
   $y = 5;

   if ($x > 5 and $y < 10) {
  echo "Both conditions are true.\n";
   }

   if ($x == 10 or $y == 20) {
  echo "At least one condition is true.\n";
   }
?>

Output

This will create the below output −

Both conditions are true.
At least one condition is true.

Using Logical Operators in a Loop

In the following example, we are using logical operators in a while loop to control the flow.

<?php
   $count = 1;

   while ($count <= 5 && $count != 3) {
  echo "Current count: $count\n";
  $count++;
   }
?>

Output

Following is the output of the above code −

Current count: 1
Current count: 2