Reading ac voltage with zmpt101b and web server page by arduno =Ethernet shield

i want to measure ac voltage and mointor and reading it from webserver page

I am using :
1-ardunio uno
2-Eethernet shield w5100
3-AC zmpt101b VOLTAG SENSOR

/*
ZMPT101B - AC Voltage sensor
Calculate Voltage

double sensorValue1 = 0;
double sensorValue2 = 0;
int crosscount = 0;
int climb_flag = 0;
int val[100];
int max_v = 0;
double VmaxD = 0;
double VeffD = 0;
double Veff = 0;

void setup() {
  Serial.begin(9600);
}

void loop() {

  for ( int i = 0; i < 100; i++ ) {
    sensorValue1 = analogRead(A0);
    if (analogRead(A0) > 511) {
      val[i] = sensorValue1;
    }
    else {
      val[i] = 0;
    }
    delay(1);
  }

  max_v = 0;

  for ( int i = 0; i < 100; i++ )
  {
    if ( val[i] > max_v )
    {
      max_v = val[i];
    }
    val[i] = 0;
  }
  if (max_v != 0) {


    VmaxD = max_v;
    VeffD = VmaxD / sqrt(2);
    Veff = (((VeffD - 420.76) / -90.24) * -210.2) + 210.2;
  }
  else {
    Veff = 0;
  }
  Serial.print("Voltage: ");
  Serial.println(Veff);
  VmaxD = 0;

  delay(100);
}

[Ttile changed to make it more appropriate - Moderator (RW)]

And THIS CODE for ethernet web server:

/*
Web Server

A simple web server that shows the value of the analog input pins.
using an Arduino Wiznet Ethernet shield.

Circuit:
* Ethernet shield attached to pins 10, 11, 12, 13
* Analog inputs attached to pins A0 through A5 (optional)

created 18 Dec 2009
by David A. Mellis
modified 9 Apr 2012
by Tom Igoe
modified 02 Sept 2015
by Arturo Guadalupi
 
*/

#include <SPI.h>
#include <Ethernet.h>

// Enter a MAC address and IP address for your controller below.
// The IP address will be dependent on your local network:
byte mac[] = {
  0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED
};
IPAddress ip(192, 168, 1, 177);

// Initialize the Ethernet server library
// with the IP address and port you want to use
// (port 80 is default for HTTP):
EthernetServer server(80);

void setup() {
  // You can use Ethernet.init(pin) to configure the CS pin
  //Ethernet.init(10);  // Most Arduino shields
  //Ethernet.init(5);   // MKR ETH shield
  //Ethernet.init(0);   // Teensy 2.0
  //Ethernet.init(20);  // Teensy++ 2.0
  //Ethernet.init(15);  // ESP8266 with Adafruit Featherwing Ethernet
  //Ethernet.init(33);  // ESP32 with Adafruit Featherwing Ethernet

  // Open serial communications and wait for port to open:
  Serial.begin(9600);
  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  }
  Serial.println("Ethernet WebServer Example");

  // start the Ethernet connection and the server:
  Ethernet.begin(mac, ip);

  // Check for Ethernet hardware present
  if (Ethernet.hardwareStatus() == EthernetNoHardware) {
    Serial.println("Ethernet shield was not found.  Sorry, can't run without hardware. :(");
    while (true) {
      delay(1); // do nothing, no point running without Ethernet hardware
    }
  }
  if (Ethernet.linkStatus() == LinkOFF) {
    Serial.println("Ethernet cable is not connected.");
  }

  // start the server
  server.begin();
  Serial.print("server is at ");
  Serial.println(Ethernet.localIP());
}


void loop() {
  // listen for incoming clients
  EthernetClient client = server.available();
  if (client) {
    Serial.println("new client");
    // an http request ends with a blank line
    boolean currentLineIsBlank = true;
    while (client.connected()) {
      if (client.available()) {
        char c = client.read();
        Serial.write(c);
        // if you've gotten to the end of the line (received a newline
        // character) and the line is blank, the http request has ended,
        // so you can send a reply
        if (c == '\n' && currentLineIsBlank) {
          // send a standard http response header
          client.println("HTTP/1.1 200 OK");
          client.println("Content-Type: text/html");
          client.println("Connection: close");  // the connection will be closed after completion of the response
          client.println("Refresh: 5");  // refresh the page automatically every 5 sec
          client.println();
          client.println("<!DOCTYPE HTML>");
          client.println("<html>");
          // output the value of each analog input pin
          for (int analogChannel = 0; analogChannel < 6; analogChannel++) {
            int sensorReading = analogRead(analogChannel);
            client.print("analog input ");
            client.print(analogChannel);
            client.print(" is ");
            client.print(sensorReading);
            client.println("<br />");
          }
          client.println("</html>");
          break;
        }
        if (c == '\n') {
          // you're starting a new line
          currentLineIsBlank = true;
        } else if (c != '\r') {
          // you've gotten a character on the current line
          currentLineIsBlank = false;
        }
      }
    }
    // give the web browser time to receive the data
    delay(1);
    // close the connection:
    client.stop();
    Serial.println("client disconnected");
  }
}
`*

You do know of course that what you are measuring there is the peak-to-peak voltage, and scaling it in the hope that it will be close to the value that is universally used for the voltage in power systems - rms (root mean square) voltage?

The libraries that we have developed and use here in OpenEnergyMonitor calculate the true rms value of both voltage and current, taking the shape of the waveform, which is not necessarily a nice text-book sinusoid, into account.