$mystring = "/var/www/html";
$test = preg_match("/^/[.]/", $mystring);

if ($test == 1)
{
    echo "ret = 1";
}
else
{
    echo "ret = 0";
}

<?php
$mystring = "/var/www/html";
$test = preg_match("/^//", $mystring);

if ($test == 1)
{
    echo "ret = 1";
}
else
{
    echo "ret = 0";
}

<?php
    $mystring = "/var/www/html";
    if(strpos($mystring,"/") === 0){
        echo "ret = 1";
    }else{
        echo "ret = 0";
    }
?>

if (substr($mystring, 0, 1) == "/") {
  echo "ret= 1";
}

echo $mystring[0] == "/" ? "ret 1" : "ret 0";

$mystring = "/var/www/html";
$test = preg_match("/^//", $mystring);

if ($test == 1)
{
    echo "ret = 1";
}
else
{
    echo "ret = 0";
}