how to make variable "?" in laravel 5.8 [duplicate]

This question already has an answer here:

• Laravel 5 making a route for a specific link 2 answers

I want to make parameters as below

for example

http://localhost/firecek_web/pengaduan?barcode=8571385

route

Route::get('/pengaduan','PengaduanController@index');

via Chebli Mohamed