Create JSON in a txt file

How do I make a .txt file into json?

$linhas = fopen ("sections.txt", "r");      


        //percorre                                 
       while (!feof ($linhas)){

         $ponteiro = fgets($linhas, 1096);
            $valores = preg_split("[/]",$ponteiro);

           $paraTxt = $valores[0];

           //não pega o ; inicial do arquivo
           $paraTxt = substr ($valores[0],1);// aqui
           // echo '<br>'. $paraTxt;


           //novo array php
           $arrSection[] = array($paraTxt);                   
             $paraJson = json_encode($arrSection);          

         }
        // $paraJson = json_encode($arrSection);

         var_dump($paraJson); 
         //fclose ($linhas); */



do jeito que fiz retornando false.

  

reader.php: 238: boolean false

Any hint of transforming this file, where it already read and scrolls in the txt format, and when I use the function to transform it into json it returns false  That in the end I want to call this array in javascript, be listed in typehead.