How to extract values from input type in php?

Question

I have a php file that gets a list of questions from a third party. It then generates questions depending on the question type. How to I extract values of name = $i and pass them to an array?

I think the problem we are having is populating all the radio buttons, since the value is $i it changes for each question.

  $max = sizeof($questions);

    for($i=0; $i<$max; $i++){
        $max2 = sizeof($questions[$i]);
        $stop = ($max2-2);


        //post to xyz
        echo "<form method = 'POST' action = 'xyz.php'>";

        // multiple choice
        if($questions[$i][0]==1)
        {

            echo $questions[$i][1];
            echo("<br>");
            echo "<input type='radio' name= '$i' value = '$questions[$i][1]'>";

            echo $questions[$i][2];
            echo("<br>");
            echo "<input type='radio' name= '$i' value = '$questions[$i][2]'>";

            echo $questions[$i][3];
            echo("<br>");
            echo "<input type='radio' name= '$i' value = '$questions[$i][3]'>";

            echo $questions[$i][4];
            echo("<br>");
            echo "<input type='radio' name= '$i' value = '$questions[$i][4]'>";

            echo $questions[$i][5];
            echo("<br>");



        }

       // true or false
        else if($questions[$i][0]==2)
        {
            echo $questions[$i][1];
            echo("<br>");
            if($questions[$i][2] == "true"){
                echo "<input type='radio' name= '$i' value = '$questions[$i][2]'>";
                echo $questions[$i][2];
                echo("<br>");
                echo "<input type='radio' name= '$i' value = '$questions[$i][2]'>";
                echo "false";
                echo("<br>");




            }

            else if($questions[$i][2] == "false"){

                echo "<input type='radio' name= '$i' value = '$questions[$i][2]'>";

                echo "true";
                echo("<br>");

                echo "<input type='radio' name= '$i' value = '$questions[$i][2]'>";
                echo $questions[$i][2];
                echo("<br>");



            }

        }

        // fill in the blank
        else if($questions[$i][0]==3)
        {
            echo $questions[$i][1];
            echo("<br>");
            echo "<input type = 'text' name ='$i'>";



        }

        //open ended    
        else if($questions[$i][0]==4)
        {
            echo $questions[$i][1];
            echo("<br>");
            echo "<input type = 'text' name ='$i'>";




        }


        for($k=0; $k<$max2; $k++){
            if($k != $stop){
            //echo($questions[$i][$k]);
                echo("<br>");
            }
            echo"<br>";
        }

    }

    echo "<input type='hidden' value= '$max' name= 'max'>";
    echo "<input type='submit' value= 'Submit Quiz'>";
    echo "</form>";

Any help is appreciated!