Logical operators in PHP - Step-by-Step Execution

Concept Flow - Logical operators

Start

↓

Evaluate operand1

↓

Evaluate operand2

↓

Apply logical operator

↓

Result: true or false

↓

Use result in condition or output

↓

End

Logical operators take two true/false values and combine them to produce a new true/false result.

Execution Sample

PHP

<?php
$a = true;
$b = false;
$result = $a && $b;
echo $result ? 'true' : 'false';
?>

This code checks if both $a and $b are true using the AND operator and prints 'true' or 'false'.

Execution Table

Step	Variable/Expression	Value	Operation	Result
1	$a	true	Assign true	true
2	$b	false	Assign false	false
3	$a && $b	true && false	Logical AND	false
4	echo	false	Output result	false

💡 All steps completed, final output is 'false' because true AND false is false.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
$a	undefined	true	true	true	true
$b	undefined	undefined	false	false	false
$result	undefined	undefined	undefined	false	false

Key Moments - 2 Insights

Why does $a && $b result in false even though $a is true?

Because logical AND (&&) requires both operands to be true. Here, $b is false, so the whole expression is false (see execution_table step 3).

What is the difference between && and || operators?

&& returns true only if both sides are true; || returns true if at least one side is true. This is shown by how $a && $b is false but $a || $b would be true.

Visual Quiz - 3 Questions

Look at the execution_table at step 3, what is the result of $a && $b?

A true

B undefined

C false

D error

💡 Hint

Check the 'Result' column in execution_table row 3.

At which step is the variable $result assigned a value?

A Step 1

B Step 3

C Step 2

D Step 4

💡 Hint

Look for the step where $result is calculated in execution_table.

If $b was true instead of false, what would be the output at step 4?

A true

B false

C undefined

D error

💡 Hint

Logical AND needs both true to output true; see variable_tracker for $b's value effect.

Concept Snapshot

Logical operators combine two boolean values.
Common operators: && (AND), || (OR), ! (NOT).
&& returns true only if both are true.
|| returns true if at least one is true.
! negates a boolean value.
Used in conditions to control program flow.

Full Transcript

This example shows how logical operators work in PHP. We start by assigning true to $a and false to $b. Then we use the logical AND operator (&&) to combine them. Since $b is false, the result of $a && $b is false. This result is stored in $result and printed as 'false'. Logical operators help us decide if conditions are met by combining true/false values. The AND operator requires both sides to be true to return true. This is why the output is false here.