diff --git a/NumberToWord.php b/NumberToWord.php
index a28fc0d..f0fd53b 100644
--- a/NumberToWord.php
+++ b/NumberToWord.php
@@ -1,132 +1,138 @@
 <?php
 
-$SPACE    = ' ';
-$DASH     = '-';
+class NumberToWord{
 
-$UNIT = array(
-	3     => 'thousand',
-	6     => 'million',
-	9     => 'billion',
-	12    => 'trillion',
-	15    => 'quadrillion',
-	18    => 'quintillion',
-	21    => 'sextillion',
-	24    => 'septillion',
-	27    => 'octillion',
-	30    => 'nonillion',
-	33    => 'decillion',
-	36    => 'undecillion',
-	39    => 'duodecillion',
-	42    => 'tredecillion',
-	45    => 'quattuordecillion',
-	48    => 'quindecillion',
-	51    => 'sexdecillion',
-	54    => 'septendecillion',
-	57    => 'octadecillion',
-	60    => 'novemdecillion',
-	63    => 'vigintillion',
-	66    => 'unvigintillion',
-	69    => 'duovigintillion',
-	72    => 'trevigintillion',
-	75    => 'quattuorvigintillion',
-	78    => 'quinvigintillion',
-	81    => 'sexvigintillion',
-	84    => 'septenvigintillion',
-	87    => 'octavigintillion',
-	90    => 'novemvigintillion',
-	93    => 'trigintillion',
-	96    => 'untrigintillion',
-	99    => 'duotrigintillion',
-	);
+	private $SPACE    = ' ';
+	private $DASH     = '-';
+	private $UNIT     = array();
+	private $WORD     = array();
 
-$WORD = array(
-    0     => 'zero',
-    1     => 'one',
-    2     => 'two',
-    3     => 'three',
-    4     => 'four',
-    5     => 'five',
-    6     => 'six',
-    7     => 'seven',
-    8     => 'eight',
-    9     => 'nine',
-    10    => 'ten',
-    11    => 'eleven',
-    12    => 'twelve',
-    13    => 'thirteen',
-    14    => 'fourteen',
-    15    => 'fifteen',
-    16    => 'sixteen',
-    17    => 'seventeen',
-    18    => 'eighteen',
-    19    => 'nineteen',
-    20    => 'twenty',
-    30    => 'thirty',
-    40    => 'fourty',
-    50    => 'fifty',
-    60    => 'sixty',
-    70    => 'seventy',
-    80    => 'eighty',
-    90    => 'ninety',
-    100   => 'hundred'
-);
+	function __construct(){
+		$this->init();
+	}
+
+	private function init(){
+		$this->UNIT = array(
+			3     => 'thousand',
+			6     => 'million',
+			9     => 'billion',
+			12    => 'trillion',
+			15    => 'quadrillion',
+			18    => 'quintillion',
+			21    => 'sextillion',
+			24    => 'septillion',
+			27    => 'octillion',
+			30    => 'nonillion',
+			33    => 'decillion',
+			36    => 'undecillion',
+			39    => 'duodecillion',
+			42    => 'tredecillion',
+			45    => 'quattuordecillion',
+			48    => 'quindecillion',
+			51    => 'sexdecillion',
+			54    => 'septendecillion',
+			57    => 'octadecillion',
+			60    => 'novemdecillion',
+			63    => 'vigintillion',
+			66    => 'unvigintillion',
+			69    => 'duovigintillion',
+			72    => 'trevigintillion',
+			75    => 'quattuorvigintillion',
+			78    => 'quinvigintillion',
+			81    => 'sexvigintillion',
+			84    => 'septenvigintillion',
+			87    => 'octavigintillion',
+			90    => 'novemvigintillion',
+			93    => 'trigintillion',
+			96    => 'untrigintillion',
+			99    => 'duotrigintillion',
+			);
 
-function convert($number){
-	global $SPACE,$DASH,$UNIT;
+		$this->WORD = array(
+		    0     => 'zero',
+		    1     => 'one',
+		    2     => 'two',
+		    3     => 'three',
+		    4     => 'four',
+		    5     => 'five',
+		    6     => 'six',
+		    7     => 'seven',
+		    8     => 'eight',
+		    9     => 'nine',
+		    10    => 'ten',
+		    11    => 'eleven',
+		    12    => 'twelve',
+		    13    => 'thirteen',
+		    14    => 'fourteen',
+		    15    => 'fifteen',
+		    16    => 'sixteen',
+		    17    => 'seventeen',
+		    18    => 'eighteen',
+		    19    => 'nineteen',
+		    20    => 'twenty',
+		    30    => 'thirty',
+		    40    => 'fourty',
+		    50    => 'fifty',
+		    60    => 'sixty',
+		    70    => 'seventy',
+		    80    => 'eighty',
+		    90    => 'ninety',
+		    100   => 'hundred'
+		);
+	}
 
-    $output="";
+	public function convert($number){
+	    $output="";
 
-	if(is_numeric($number)){
-		$number=str_replace('+', '', $number);
-		$number=str_replace('-', '', $number);
-		$number=str_replace('.', '', $number);
-		$len=strlen($number);
+		if(is_numeric($number)){
+			$number=str_replace('+', '', $number);
+			$number=str_replace('-', '', $number);
+			$number=str_replace('.', '', $number);
+			$len=strlen($number);
 
-		if($len<=99){
-			for($i=$len;$i>0;$i-=3){
-				$pos=3*((int)($len/3)-(int)($i/3));
-				$start=$i-3;
-				$stop=3;
-				if($start<0){
-					$stop=3+$start;
-					$start=0;
+			if($len<=99){
+				for($i=$len;$i>0;$i-=3){
+					$pos=3*((int)($len/3)-(int)($i/3));
+					$start=$i-3;
+					$stop=3;
+					if($start<0){
+						$stop=3+$start;
+						$start=0;
+					}
+					$temp=$this->loop(substr($number,$start,$stop)).$this->SPACE;
+					if($i!=$len) $temp.=$this->UNIT[$pos].$this->SPACE;
+					$output=$temp.$output;
 				}
-				$temp=loop(substr($number,$start,$stop)).$SPACE;
-				if($i!=$len) $temp.=$UNIT[$pos].$SPACE;
-				$output=$temp.$output;
+				return $output;
+			}else{
+				throw new Exception("too big number, maximum string length is 99", 1);
 			}
-			$output='{"status":"success", "input":"'.$number.'", "output":"'.$output.'"}';
 		}else{
-			$output='{"status":"error", "input":"'.$number.'", "output":"too big number"}';
+			throw new Exception("not a valid number", 1);
 		}
-	}else{
-		$output='{"status":"error", "input":"'.$number.'", "output":"not a valid number"}';
 	}
-	return $output;
-}
 
-function loop($number){
-	global $SPACE,$DASH,$WORD;
+	private function loop($number){
+		$number=(int)$number;
+	    $output="";
 
-	$number=(int)$number;
-    $output="";
-
-    if($number<=20){
-		$output=$WORD[$number];
-	}elseif($number<=99){
-		$base=10;
-		$main=$number/$base;
-		$rest=$number%$base;
-		$output=$WORD[(int)$main*$base];
-		if($rest) $output.=$DASH.$WORD[$rest];
-	}else{
-		$base=100;
-		$main=$number/$base;
-		$rest=$number%$base;
-		$output=loop((int)$main).$SPACE.$WORD[$base];
-		if($rest) $output.=$SPACE.loop($rest);
+	    if($number<=20){
+			$output=$this->WORD[$number];
+		}elseif($number<=99){
+			$base=10;
+			$main=$number/$base;
+			$rest=$number%$base;
+			$output=$this->WORD[(int)$main*$base];
+			if($rest) $output.=$this->DASH.$this->WORD[$rest];
+		}else{
+			$base=100;
+			$main=$number/$base;
+			$rest=$number%$base;
+			$output=$this->loop((int)$main).$this->SPACE.$this->WORD[$base];
+			if($rest) $output.=$this->SPACE.$this->loop($rest);
+		}
+		return $output;
 	}
-	return $output;
 }
 
 ?>
\ No newline at end of file
diff --git a/README.md b/README.md
index ccb17f8..90d4c83 100644
--- a/README.md
+++ b/README.md
@@ -4,35 +4,30 @@ A php file to convert any number to word form.
 # Documentation
 You can find the documentation at https://nfraz007.github.io/NumberToWord/
 
-## Setup
+# Setup
 
-First, import the file NumberToWord.php
+Setup is very easy, just import the file into your project and you are all set.
 
 ```
-require 'NumberToWord.php';
+include("NumberToWord.php");
 ```
 
-### Function name and parameter
-To convert any number to its word form, you have to call a function convert(), which take one parameter as string and give a output in json. Please see the function detail given below.
+or
 
-name : convert()
+```
+require 'NumberToWord.php';
+```
 
-input : string
+# Convert a number
+To convert any number to its word form, create an instance of NumberToWord class. you can then call the convert() function on the NumberToWord object, passing one parameter as number you want to convert
 
-output : json
+* Input must be a integer value in string format.
 
-### Maximum limit of length of input string = 99
+* **Maximum limit of length of input string = 99**
 
-### Convert number
 ```
-  // call convert(string) funtion, it will return a json string.
-  $output = convert('123');
-  $output = convert('1a');
-  $output = convert('0');
-  
-  /*
-    {"status":"success", "input":"123", "output":"one hundred twenty-three"}
-    {"status":"error", "input":"1a", "output":"not a valid number"}
-    {"status":"success", "input":"0", "output":"zero"}
-  */
+$obj = new NumberToWord();
+echo $obj->convert("123");
 ```
+
+> one hundred twenty-three
\ No newline at end of file
diff --git a/index.php b/index.php
index 7b62560..d3d0525 100644
--- a/index.php
+++ b/index.php
@@ -1,6 +1,8 @@
 <?php
 require_once 'NumberToWord.php';
 
-$number=123;
-echo convert($number);
+$number='123';
+$obj=new NumberToWord();
+
+echo $obj->convert($number);
 ?>
\ No newline at end of file