Pass PHP variable created in one function to another

You could make the variable global:

function add_custom_price( $cart_object ) {    global $newVar;    foreach ( $cart_object->cart_contents as $key => $value ) {        $newVar = $value['data']->price;    }}function function_name() {    global $newVar;    echo $newVar;}

Or, if $newVar is already available in the global scope you could do:

function function_name($newVar) {    echo $newVar;}// Add the hookadd_action( 'another_area', 'function_name' );// Trigger the hook with the $newVar;do_action('another_area', $newVar);

Any reason why you can't call your function from within your foreach loop?

function add_custom_price( $cart_object ) {    foreach ( $cart_object->cart_contents as $key => $value ) {        $newVar = $value['data']->price;        function_name($newVar);    }}

You should use return $variable in your functions:

function add_custom_price( $cart_object ) {  foreach ( $cart_object->cart_contents as $key => $value ) {    $newVar = $value['data']->price;  }  return $newVar;}function function_name($newVar) {//do something with $newVar}

And use like this:

$variable = add_custom_price( $cart_object );$xxx = function_name($variable);

UPDATE:

Looking at what @ChunkyBaconPlz said $newVar should be an array:

function add_custom_price( $cart_object ) {  foreach ( $cart_object->cart_contents as $key => $value ) {    $newVar[] = $value['data']->price;  }  return $newVar;}