Comparing user input with PHP array

Question

For a small project I'm working on I want a user to be able to register an account using a username however I don't want to configure a database i.e I just want to compare the username the user inputs with a PHP array.

<?php
$a=array("user1","user2");
for($a =0; $x<$arrlength; $a++){
if($username == $a){ //i want to say if $username is in array alert this and do nothing
$echo print a new username, already taken;
return false;
else(
array_push($a,username);?>

I'm working with the w3 schools PHP examples and I have something like this (the user inputs a 'username' in a form. I was wondering how you would actually implement this functionality properly.

You would still need to store the user list somewhere if you want to permanently store the user. A database is the best way. But if you really don't want to use a database, then you would have to store it in a flat text file. You could do something like file_put_contents('users.txt', serialize($a)) at the end of the file to store the contents of $a in users.txt. Then in the beginning of the file you would do $a=unserialize(file_get_contents('users.txt')); — Cave Johnson
– Cave Johnson, Commented May 23, 2016 at 23:08

Geoherna · Accepted Answer · 2016-05-23 23:07:14Z

4

You could simply use the in_array() function:

<?php
$usernames = array("user1", "user2", "user3", "user4");

if (in_array("username_from_user_input", $usernames)) {
    echo "Got Username";
}else{
    echo "Username not found"
}

?>

answered May 23, 2016 at 23:07

Geoherna

3,6241 gold badge26 silver badges41 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Jon Over a year ago

Thanks George that's what i was looking for and it makes sense. It's only a small little test i'm doing (i'm new to PHP) for myself thanks for the help!

Drellgor Over a year ago

Sometimes the simplest answer is the best answer.

M_T · Accepted Answer · 2016-05-23 23:09:02Z

2

If you want to save the registered accounts across requests, you have to store them in a file or database (or something else..), because the script is run from start on every requests.

Instead of looping over the array, you could also use the in_array function. ( http://php.net/manual/de/function.in-array.php )

To store the usernames, take a look at the file functions. (e.g. http://php.net/manual/en/function.file-put-contents.php to write to a file, and file_get_contents or file(..) to read a file). (For real projects, make sure to lock the file to prevent race conditions.)

answered May 23, 2016 at 23:09

M_T

3972 silver badges6 bronze badges

1 Comment

Cave Johnson Over a year ago

S/he should also consider blocking access to the file on the server.

Pedro Lobito · Accepted Answer · 2016-05-23 23:56:35Z

1

Late answer, but because I'm on a ternary mood, here it goes:

echo (in_array("someuser", array("user1","user2"))) ? "Got Username" : "Username not found";

edited May 23, 2016 at 23:56

answered May 23, 2016 at 23:40

Pedro Lobito

99.8k36 gold badges274 silver badges278 bronze badges

1 Comment

Darren Over a year ago

Got my vote as it's a valid alternative (not to mention I love ternary too ;-))

Fred Willmore · Accepted Answer · 2016-05-23 23:07:14Z

0

You can use in_array:

if (in_array($username, $a){
  ...
}

answered May 23, 2016 at 23:07

Fred Willmore

4,6461 gold badge33 silver badges36 bronze badges

Comments

frankfullstack · Accepted Answer · 2016-05-23 23:18:27Z

0

Try the solution of the other users but you could combine with Traits.

You could create a Trait called VerifyUser with the next content:

trait VerifyUser {
    public function verifyUser($user){
        if (in_array($username, $usersArray)){
            echo $username . "is already taken";
        }else {
            array_push($usersArray, $username);
        }
    }
}

Don't forget add your custom array to your class if you are working in a OOP environment. Add this trait with the use VerifyUser instruction.

class UsersCollection{
    use VerifyUsers

    $usersArray= ["user1", "user2"];

    $this->verifyUser("user1"); //It echo the custom message you could return a boolean value and then specify a custom behaviour.
}

answered May 23, 2016 at 23:18

frankfullstack

5708 silver badges22 bronze badges

2 Comments

Cave Johnson Over a year ago

I think this is way too advanced for someone new to PHP.

frankfullstack Over a year ago

Correct, but I only answered this need and may be useful for other users newbies or advanced. The answer is use the in_array function but I only exposed a way to improve this, facilitating the code reusability.

Collectives™ on Stack Overflow

Comparing user input with PHP array

5 Answers 5

2 Comments

1 Comment

1 Comment

Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

5 Answers 5

2 Comments

1 Comment

1 Comment

Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related