What are the differences between isset(), empty(), and is_null() functions in PHP?

The isset() function checks if a variable is set and is not NULL, while the empty() function checks if a variable is empty (i.e., evaluates to false). The is_null() function specifically checks if a variable is NULL. It's important to use the appropriate function based on the specific condition you are checking for in your PHP code. 

// Example demonstrating the differences between isset(), empty(), and is_null() functions
$var1 = "";
$var2 = null;

// isset() example
if(isset($var1)){
    echo '$var1 is set';
} else {
    echo '$var1 is not set';
}

// empty() example
if(empty($var1)){
    echo '$var1 is empty';
} else {
    echo '$var1 is not empty';
}

// is_null() example
if(is_null($var2)){
    echo '$var2 is NULL';
} else {
    echo '$var2 is not NULL';
}

Keywords

isset empty is_null functions PHP

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