Validate alphanumeric strings in PHP

Question

I'm not sure if alphanumeric is the correct term but I would like to validate characters that are in a combination of strings, integers and dashes. Example: yui-4444-99. So far, i've tried intval, strcmp, ctype_alnum and preg_match but it doesnt really work.

sample:

<?php
if (ctype_alnum($string1) == ctype_alnum($string2)) {
    echo "nice!";       
} else {
}

my txt.file

abc-1234-99
Cedric
93482812
[email protected]
---------------------------------------------
def-4332-99
Wendy
98238432
[email protected]
Guitar
2010
Yamaha
Scratches on the side
Used
---------------------------------------------
fgh-4567-99
Wendy
98238432
[email protected]
---------------------------------------------
yui-4444-99
Wendy
98238432
[email protected]
---------------------------------------------
vbn-5624-99
jason
98238432
[email protected]
---------------------------------------------

This is how i extracted my values to diff variables.

<?php
    
$handle = @fopen('listings.txt', "r");
$row = 0;
$count = 0;
$line0 = [];
$line1 = [];
$line2 = [];
$line3 = [];
$line4 = [];
$line5 = [];
$line6 = [];
$line7 = [];
$line8 = [];
$line9 = [];
    
if ($handle) { 
   while (!feof($handle)) { 
       $store = fgets($handle, 4096); 
       if ($row == 10){
        $row = 0;
        $count++;
    }
    if ($row == 0) 
    {
        $line0[] = strval($store);
    }
    else if($row == 1) {
$line1[] = strval($store);}
    else if($row == 2) {
$line2[] = strval($store);}
    else if($row == 3) {
$line3[] = strval($store);}
    else if($row == 4) {
$line4[] = strval($store);}
    else if($row == 5) {
$line5[] = strval($store);}
    else if($row == 6) {
$line6[] = strval($store);}
    else if($row == 7) {
$line7[] = strval($store);}
    else if($row == 8) {
$line8[] = strval($store);}
    
    $row++;
   }
        
      $sn = 0;
      
      
    if (isset($_GET['sn'])) {
        $sn=$_GET['sn'];
    }
      $item = count($line0);
      
        for ($c=0; $c<$item; $c++)
    {
        if((intval($line0[$c]) == intval($sn))) {
        echo $line0[$c],"<br>";
        echo $line1[$c],"<br>";
        echo $line2[$c],"<br>";
        echo $line3[$c],"<br>";
        echo $line4[$c],"<br>";
        echo $line5[$c],"<br>";
        echo $line6[$c],"<br>";
        echo $line7[$c],"<br>";
        echo $line8[$c],"<br>";
        break;
        }
    }
    ?>

    
    
    
    <?php
   fclose($handle); 
} 

    ?>

yes, to make sure both are these variables have the same characters — Kinja
– Kinja, Commented Jan 20, 2021 at 7:04
ok sir hold on, its abit more complicated than that, i apologize for not elaborating — Kinja
– Kinja, Commented Jan 20, 2021 at 7:08
So, im doing a search box, so the 1st variable will be the text entered and it will pass it over to the result page where it will compare it with the 2nd variable. — Kinja
– Kinja, Commented Jan 20, 2021 at 7:09

Code4R7 · Accepted Answer · 2021-01-20 07:26:25Z

2

Starting from PHP 8, you can compare strings to their numeric equivalent:

$test = ['', 'a23', '23', 'abc'];
foreach ($test as $string) {
  echo ($string != (int) $string ? 'TRUE' : 'FALSE') . PHP_EOL;
}

Output:

TRUE
TRUE
FALSE
TRUE

answered Jan 20, 2021 at 7:26

Code4R7

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Comments

Death-is-the-real-truth · Accepted Answer · 2021-01-20 11:47:05Z

1

You need to shorten out code of reading file using file().

Also needs to rectify comparison code as well.

Do like below:

<?php

$string2 = file('listings.txt', FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);

$foundArray = [];

foreach($string2 as $string){
    if (ctype_alnum($string1) == ctype_alnum($string)) {
        $foundArray[] = $string; 
    }
}

echo "found matches :".print_r($foundArray,true);

Sample output: https://3v4l.org/Vt4OE

edited Jan 20, 2021 at 11:47

answered Jan 20, 2021 at 9:04

Death-is-the-real-truth

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Comments

azibom · Accepted Answer · 2021-01-20 07:30:22Z

1

If you want to just compare the first part of them, you can use this code:

<?php
$string1 = "sdf-98-s";
$stringArray = ["sdf", "asd"];

$myArray = explode('-', $string1); // make the array from string
$firstElement = reset($myArray); // choose the first element

if (in_array($firstElement, $stringArray)) {
    echo "Find it!";       
} else {
    echo "Fail to find it!";       
}

edited Jan 20, 2021 at 7:30

answered Jan 20, 2021 at 7:07

azibom

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3 Comments

Kinja Over a year ago

so the only way is to explode the dashes so it can validate?

azibom Over a year ago

what is the problem with this solution?

Kinja Over a year ago

my 2nd variable which is $string2 will be reading an array of these strings from a txt.file. so my search box text which is $string1 will have to compare with all the other strings in my txt.file.

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