$arr=array("blah1","blah2","blah3");
$fp=fopen("test.txt","w+");
foreach($arr as $key => $value)
{
fwrite($fp,$value."\t");
}
$file = 'people.txt';
// The new person to add to the file
$person = "John Smith\n";
// Write the contents to the file,
// using the FILE_APPEND flag to append the content to the end of the file
// and the LOCK_EX flag to prevent anyone else writing to the file at the same time
file_put_contents($file, $person, FILE_APPEND | LOCK_EX);