store_and_get_data_from_file.php

<?php
// for data add
function add_data($id,$name,$phone){
    $data =  sprintf('%10d%60s%15s',$id,$name,$phone);
    $file = fopen('db.txt','a');
    fwrite($file,$data);
    fclose($file);
}


if (isset($_GET['add-data'])){
    $id = $_GET['id']+0;
    $name= $_GET['name'];
    $phone = $_GET['phone'];
    add_data($id,$name,$phone);

}
?>
<?php
// for data show
$file = fopen('db.txt','r');
$filesize = filesize('db.txt');
$data = fread($file,$filesize);
fclose($file);
echo $data;
$ln = strlen($data);
for ($i=0; ; $i++){
    $start = $i*85;
    $extra = 85;
    if ($start+$extra > $ln){
        break;
    }

    $student_info = substr($data,$start,$extra);
    $id =trim(substr($student_info,0,10));
    $name =trim(substr($student_info,10,60));
    $phone =trim(substr($student_info,70,15));
    echo "<br>id: $id - Name: $name - Phone: $phone";

}
?>

<form action="" method="GET">
    <input type="number" name="id" placeholder="id">
    <input type="text" name="name" placeholder="name">
    <input type="text" name="phone" placeholder="phone">
    <input type="submit" name="add-data" value="Add">
</form>