How to call a function from a string stored in a variable?

Question

I need to be able to call a function, but the function name is stored in a variable, is this possible? e.g:

function foo ()
{
    //code here
}

function bar ()
{
    //code here
}

$functionName = "foo";
// I need to call the function based on what is $functionName

Answer 1

$functionName() or call_user_func($functionName)

If you need to provide parameters stored in another variable (in the form of array), use array unpacking operator:

$function_name = 'trim';
$parameters = ['aaabbb','b'];
echo $function_name(...$parameters); // aaa

To dynamically create an object and call its method use

$class = 'DateTime';
$method = 'format';
echo (new $class)->$method('d-m-Y');

or to call a static method

$class = 'DateTime';
$static = 'createFromFormat';
$date = $class::$static('d-m-Y', '17-08-2023');