Question

Anyone can show me why this piece of code works with the second line but not the first line, although they are the same?

Here is the pass.txt file:

01234567 5f4dcc3b5aa765d61d8327deb882cf99
01234567 5f4dcc3b5aa765d61d8327deb882cf99

Here’s the code:

<?php
    $f = fopen("pass.txt", "r");
    if ($f) {
        $buffer = fgets($f);
        $buffer = fgets($f); //Comment out this line to read the first line

        $token = explode(' ', $buffer);
        if ($token[1] == hash('md5', 'password'))
            echo "Password correct";
        else
            echo "Password incorrect";
    }
?>

Answer 1

As @David Schwartz pointed out, the most possible reason is the newline character.

You could use file function to ignore the newline char.

foreach (file('pass.txt', FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES) as $line) {
    $token = explode(' ', $line);
    if ($token[1] == hash('md5', 'password'))
      echo "Password correct";
    else
      echo "Password incorrect";
} 

If the file is very large, then use fgets to read it one by one and trim the newline.