php cannot work with a substring

Question

I`m making a php file to generate users and inserting them in a database. The first thing I made is to obtain the latest one and save it in a variable, then, I use a function to obtain the integer part of the string and increment that value by one, but that is the part that I think is not working.

This is the code:

<?php

$con = new mysqli('localhost', 'root', '', 'prueba');

function create_user($var){
    $prefix = "U";
    for($i = 0; $i < 5- strlen((String)$var); $i++) {
         $prefix .= '0';
    }
    $var = mb_substr($var, 1);

    if(is_numeric($var)) {
        $int = $var++;
        $var = $prefix . $int;
    }
    return $var;
}

$execute = mysqli_query($con, "select id_user from usuarios
    WHERE id_user=(SELECT MAX(id_user) FROM usuarios)");

$row = mysqli_fetch_array($execute);
print_r($row['id_user']);
$var1 = $row['id_user'];

$userid=create_user($var1);

mysqli_query($con, "insert into usuarios (password, descripcion, id_user) 
    values ('A12345a', 'hgfhdgfh', ' $userid' )");

echo "hecho";
?>

Any help, please?

Why are you mix and matching mb_* and non-mb_* functions...? — Mark Baker
– Mark Baker, Commented Jul 9, 2013 at 9:22
Please give an example of the string before it is passed to create_user() and after. — RiggsFolly
– RiggsFolly, Commented Jul 9, 2013 at 9:30
Ok but what is passed INTO the function? An actual value In and out would be useful. — RiggsFolly
– RiggsFolly, Commented Jul 9, 2013 at 10:38

Expedito · Accepted Answer · 2013-07-09 09:31:05Z

1

Change this line:

$int = $var++;

to:

$int = ++$var;

It's assigning the value of $var before incrementing.

answered Jul 9, 2013 at 9:31

Expedito

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