How to check whether a variable is empty in PHP?

To check whether a variable is empty in PHP, you can use the empty() function. This function returns true if the variable is empty, and false otherwise.

A variable is considered empty if it is:

• null
• an empty string ('')
• a string of whitespaces (' ')
• an empty array (array())
• a number that is equal to 0 (0, 0.0, 0e0)
• a boolean that is equal to false

For example:

$var = '';

if (empty($var)) {
    echo '$var is empty';
} else {
    echo '$var is not empty';
}

This would output $var is empty.

You can also use the isset() function to check whether a variable is set and is not null. This function returns true if the variable is set and is not null, and false otherwise.

For example:

$var = '';

if (isset($var)) {
    echo '$var is set';
} else {
    echo '$var is not set';
}

This would output $var is set.