如何将两个或多个值/变量连接到laravel中的新变量

I am pretty much new to laravel(5.2), here i want to concatenate two values say first name and last name during user registration and save it to database, honestly as am new to this whole concept i have very little idea of doing it...it would be great if i could get some help....

User.php

class User extends Authenticatable
{
    /**
     * The attributes that are mass assignable.
     *
     * @var array
     */
    protected $fillable = [
        'first_name', 'last_name', 'email'
    ];

    /**
     * The attributes that should be hidden for arrays.
     *
     * @var array
     */
    protected $hidden = [
        'password', 'remember_token',
    ];
}

AuthController.php

class AuthController extends Controller
{
  protected function validator(array $data)
    {
        return Validator::make($data, [
            'first_name' => 'required|max:255',
            'last_name' => 'required|max:255',
            'email' => 'required|email|max:255|unique:users',
            'password' => 'required|min:6|confirmed',
             ]);
    }

protected function create(array $data)
    {
        return User::create([
            'first_name' => $data['first_name'],
            'last_name' => $data['last_name'],
            'email' => $data['email'],
            'password' => bcrypt($data['password']),
             ]);
    }
}

if you want to save the new value to data base you must register it in you fillable, also to alter the database to accept the new column

protected $fillable = [
    'user_name', 'first_name', 'last_name', 'email'
];


protected function create(array $data)
{
    return User::create([
        'user_name' => $data['first_name'].' '.$data['last_name'],
        'first_name' => $data['first_name'],
        'last_name' => $data['last_name'],
        'email' => $data['email'],
        'password' => bcrypt($data['password']),
         ]);
}

you may want to remove first_name and last_name.. and store only full name, or you can ignore storing the full name, and in User.php model you can override the toArray() method and make it returns the full name which you can concatenate just like above

Concatenation of two strings in a php concept, it do not relates to laravel in any way. You can easily concatenate two or more string like:

$str = $data['first_name'].' '.$data['last_name'];   // concatenate by using space

But this does not help you because you are inserting user data into user table which have first_name, last_name columns. So you have to insert them individually.