Encoding issue with PHP while writing in a .csv file

I'm working with a php array which contains some values parsed from a previous scraping process (using Simple HTML DOM Parser). I can normally print / echo the values of this array, which contains special chars é,à,è, etc. BUT, the problem is the following :

When I'm using fwrite to save values in a .csv file, some characters are not successfully saved. For example, Székesfehérvár is well displayed on my php view in HTML, but saved as Székesfehérvár in the .csv file which I generate with the php script above.

I've already set-up several things in the php script :

• The page I'm scraping seems to be utf-8 encoded
• My PHP script is also declared as utf-8 in the header
• I've tried a lot of iconv and mb_encode methods in different places in the code
• NOTE that when I'm make a JS console.log of my php array, using json_encode, the characters are also broken, maybe linked to the original encoding of the page I'm scraping?

Here's a part of the script, it is the part who is writing values in a .csv file

<?php $data = array(            array("item1", "item2"),             array("item1", "item2"),            array("item1", "item2"),            array("item1", "item2")            // ...);//filename$filename = 'myFileName.csv';foreach($data as $line) {    $string_txt = ""; //declares the content of the .csv as a string    foreach($line as $item) {        //writes a new line of the .csv        $line_txt = "";        //each line of the .csv equals to the values of the php subarray, tab separated        $line_txt .= $item . "\t";    }    //PHP endline constant, indicates the next line of the .csv    $line_txt .= PHP_EOL;    //add the line to the string which is the global content of the .csv    $line_txt .= $string_txt;}//writing the string in a .csv file $file = fopen($filename, 'w+');fwrite($file, $string_txt);fclose($file);

I am currently stuck because I can't save values with accentuated characters correctly.