[Solved] i need a PHP code to find longest contiguous sequence of characters in the string

Since you’re looking for continuous sequences:

$string = 'aaabababbbbbaaaaabbbbbbbbaa';

$count = strlen($string);
if ($count > 0)
{

    $mostFrequentChar = $curChar = $string[0];
    $maxFreq = $curFreq = 1;
    for ($i = 1; $i < $count; $i++)
    {
        if ($string[$i] == $curChar)
        {
            $curFreq++;
            if ($curFreq > $maxFreq)
            {
                $mostFrequentChar = $curChar;
                $maxFreq = $curFreq;
            }
        }
        else
        {
            $curChar = $string[$i];
            $curFreq = 1;
        }
    }

}

echo $mostFrequentChar . ' ' . $maxFreq;