how to calculate the number of matches of files which have different values in php

Question

For a multiple choice exam, i store the data in .txt files.

I have 8 .txt files in which stored 2 or more numbers. The name of the txt files are 1.txt, 2.txt, 3.txt ...

The first number in each txt file is ALWAYS the correct answer. I want to compare this first number with the last number of that txt file.

foreach($all_files as $file) {
    $each_file = file_get_contents($file);
    $choosen_answer = substr($each_file, -1); // last number is the number user has choosen
    $correct_answer = substr($each_file, 0,1); // first number is the correct answer

    // output the answers
    echo '<span class="choosen_answer">'.$choosen_answer.'</span>'; 
    echo '<span class="correct_answer">'.$correct_answer.'</span>';

    $wrong = 0;
    if($choosen_answer != $correct_answer) { // compare the 2 values
        $wrong++;
        echo '<span class="wrong text-danger">Wrong</span>';
    }
    else {
        echo '<span class="correct text-success">Correct</span>';
    }

}
echo count($wrong); // this should give me the number of wrong answers, but it does not...

I want to calculate the number of wrong answers and i tried count($wrong); for this but it does not give me the number of wrong answers.

So what i need: if 3 of the 8 questions are wrong answered, it should give me the number 3

Each txt file looks like this:

02 // 0 is the correct answer, 2 is the answer from the user. I compare 0 with 2. So wrong answer

or

14 // 1 is the correct answer. 4 is the answer of the user. I compare 1 with 4. So wrong answer

or

22 // 2 is the correct answer. 2 is also the answer of the user. So correct answer

Answer 1

$wrong = 0; is in the foreach loop! so after every iteration, it makes it 0 again.

Your code should look like:

$wrong = 0;
foreach($all_files as $file) {
    $each_file = file_get_contents($file);
    $choosen_answer = substr($each_file, -1); // last number is the number user has choosen
    $correct_answer = substr($each_file, 0,1); // first number is the correct answer

    // output the answers
    echo '<span class="choosen_answer">'.$choosen_answer.'</span>'; 
    echo '<span class="correct_answer">'.$correct_answer.'</span>';

    if($choosen_answer != $correct_answer) { // compare the 2 values
        $wrong++;
        echo '<span class="wrong text-danger">Wrong</span>';
    }
    else {
        echo '<span class="correct text-success">Correct</span>';
    }

}
echo $wrong;