How to pass a variable to a function with callback?

What is $data? What you have shown here is just a definition of a parameter your anonymous function is expecting, but you don't have it anywhere inside the body of the doIt() function that's actually using it. That's what the error is telling you. If you have $data defined inside doIt(), everything shall work as expected.

its hard to find something like this when you don't know what to search for.

You can pass values to the closure with use

doIt(function() use($data) {
    echo 'Anonymous function: ' . $data;
});

Stil not sure what its called

@SNAPEY - Hmm, still getting an error

NOTICE Undefined variable: data on line number 7

WARNING Missing argument 1 for {closure}(), called in /home4/phptest/public_html/code.php70(5) : eval()'d code on line 4 and defined on line number 7
Anonymous function!

Code:

function doIt($callback) { 
    $callback(); 
} 

doIt(function($data) use ($data) {
    echo 'Anonymous function!' . $data;
});

you are not passing anything to the callback, but expecting it in doIt

check my example

@SNAPEY - I got it to work. However I have seen code without the use keyword like this. How do they do it?

function doIt($callback) { 
    $callback(); 
}

$data = 'my data here...';

doIt(function($data) {
    echo 'Anonymous function!' . $data;
});

This is giving me these errors:

WARNING Missing argument 1 for {closure}(), called in /home4/phptest/public_html/code.php70(5) : eval()'d code on line 4 and defined on line number 9

NOTICE Undefined variable: data on line number 10

@MARTINZELTIN - Both approaches work well:

function doIt($callback)
{
    $callback();
}

$data = 'my data here...';

doIt(function () use ($data) {
    echo 'Anonymous function!' . $data;
});

$data = 'my data here...';

$doIt = function () use ($data) {

    echo 'Anonymous function! ' . $data;
};

$doIt();

Why not u use the second argument to pass the data

function doIt($callback, $data) {
    $callback($data);
}



doIt(function($data) {
    echo 'Anonymous function: ' . $data;
}, "Your data will go here");

@KUNDEFINE - Yes!!! Thank you! That's what I was looking for! Like Snapey said, it's hard to find something when you don't know what to search for.

function doIt($data, $callback) {
    $callback($data);
}


doIt('my data', function($data) {
    echo 'Anonymous function: ' . $data;
});