完全停止后接近100个单词的分页符的PHP代码

Question

I have a test area which is dynamic text from database may be of thousands of words. I want it to break and make a paragraph of each with full stop near 100(any length) words. I am able to make break after 100 words but not with full stop. To make break after 100(any length) words I used the following function.

function TrimString($String, $Length)
{
    if(strlen($String) > $Length)
    {
        $Temp[0] = substr($String, 0, $Length);
        $Temp[1] = substr($String, $Length);
        $SpacePos = strpos($Temp[1], ' ');
        if($SpacePos !== FALSE)
        {
            return $Temp[0].substr($Temp[1], 0, $SpacePos);
        }
    }
    return $String;
}

example:-

function TrimString($String, $Length){
    if(strlen($String)<=$Length){
        $stringValue=$String;
    } else {
        $stringValue=substr($String,0,$Length) . '.';
    }
    return $stringValue;
}
$m=50;
$a="I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. ";
$data=TrimString($a,$m);
echo $data;

It provides me the answer

I am a boy. I am a boy. I am a boy. I am a boy. I .

but i need the answer

I am a boy. I am a boy. I am a boy. I am a boy.

So can you help me to find the full stop near to the length provided to that function and to break the paragraph.

Answer 1

add full stop(.) here like

 return $Temp[0].substr($Temp[1], 0, $SpacePos).".";

UPDATE 2 :

<?php
function TrimString($String, $Length){
    if(strlen($String)<=$Length){
        $stringValue=$String;
    } else {
        $new_l = strpos ($String , ".", $Length);
        $Length = $new_l+1;
        $stringValue=substr($String,0,$Length);
    }
    return $stringValue;
}
$m=50;
$a="I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. I am a boy. ";
$data=TrimString($a,$m);
echo $data;
?>

OUTPUT :

I am a boy. I am a boy. I am a boy. I am a boy. I am a boy.