file(); //Browse a file and put it in an array
fopen(); //open a file

<?php
// we declare the name of the file
$myfile = 'myfile1.txt'; 
//we count the size of the file
$its_size = filesize($myfile); 

//open the file for read only
$fp = fopen($myfile,'r'); 
//feof shows the end of the file...
//So it reading the file until the end.
while( !feof($fp) ) 
{

//reading the file and putting it on the variable line.
$line = fgets($fp,$taille); 
//display the line  affiche la line..

/Do not forget to put the <br> for the next line.

print $ligne.'<br />'; 
}
//we close at the end
fclose($fp); 
?>

<?php
// we declare the name of the file
$myfile = 'myfile1.txt'; 
//open the file to write and delete the data that was on it before
$fp = fopen($fichier,'w'); 

//we write on the file, the \n tells the function to move to another line.
 fwrite($fp,"my first line \n my second line"); 
//at the end we close the file
fclose($fp); 

?>

<?php
//declare the file
$myfile = 'counter.txt';
// here we use the file() function that puts the file content...
// as an array on the $fp variable.
$fp = file($myfile);

//because it's a counter, we will read just the first line on the file...
// where the number is $fp[0].
// For each new visit, we add 1 to the actual number.
$counterr = $fp['0'] + 1;
 //open the file to write.
$new = fopen($myfile,'w+');

//delete the old content and write the new number on the file, 
fwrite($new,"$counter \n");
//close the file
fclose($new); 
?>