What about functions without return statements? Any function without a return returns a special value NULL. NULL is a special data type that stands for the absence of a value.

function returnNothing() 
{
  echo "I'm running! I'm running!\n";
}

$result = returnNothing(); // Prints: I'm running! I'm running!

echo $result; // Nothing is printed

Let’s walk through the code above:

• We defined a function returnNothing()— the returnNothing() function prints "I'm running! I'm running!\n" but has no return statement.
• We defined the variable $result and assigned it the value returned when we invoke returnNothing().
• Since we invoked the function, I'm running! I'm running! is printed.
• Because the function does not have a return statement, the value assigned to $result is NULL
• Finally, we print the $result variable, but, since its value is NULL, nothing is printed.

Let’s play around with NULL!