What are the best practices for defining and comparing variables in PHP to avoid unexpected results?

When defining and comparing variables in PHP, it is important to ensure that you are using the correct comparison operators and data types to avoid unexpected results. To compare variables, always use strict comparison operators (=== and !==) to check both the value and data type. Additionally, make sure to properly initialize and assign values to variables before comparing them.

// Define and compare variables using strict comparison operators
$var1 = 10;
$var2 = '10';

if ($var1 === $var2) {
    echo 'Variables are equal in value and type';
} else {
    echo 'Variables are not equal in value or type';
}