How to extract value into String in HTML body tag

Projects Programming
1

I have webpage like below, This is the web address of the webpage.

<!DOCTYPE html>
<html>
<body>

1,0,1,0,255,236,28,20

</body>
</html>

Now i want to save the text in the HTML body tag to string..Like below,

String outputStr = "1,0,1,0,255,236,28,20";

Also I tried to below code.. but it's not work..

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

byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
// if you don't want to use DNS (and reduce your sketch size)
// use the numeric IP instead of the name for the server:
//IPAddress server(74,125,232,128);  // numeric IP for Google (no DNS)
char server[] = "automation.sldroid.com";    // name address for Google (using DNS)

// Set the static IP address to use if the DHCP fails to assign
IPAddress ip(192, 168,1, 177);

// Initialize the Ethernet client library
// with the IP address and port of the server
// that you want to connect to (port 80 is default for HTTP):
EthernetClient client;

String readString = String(100);

void setup() {
  // 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
  }

  // start the Ethernet connection:
  if (Ethernet.begin(mac) == 0) {
    Serial.println("Failed to configure Ethernet using DHCP");
    // try to congifure using IP address instead of DHCP:
    Ethernet.begin(mac, ip);
  }
  // give the Ethernet shield a second to initialize:
  delay(1000);
  Serial.println("connecting...");

  // if you get a connection, report back via serial:
  if (client.connect(server, 80)) {
    Serial.println("connected");
    // Make a HTTP request:
    client.println("GET /get.php HTTP/1.1");
    client.println("Host: automation.sldroid.com");
    client.println("Connection: close");
    client.println();
  } else {
    // if you didn't get a connection to the server:
    Serial.println("connection failed");
  }
}

String val = String(20);

void loop() {
  
  // if there are incoming bytes available
  // from the server, read them and print them:
  if (client.available()) {
    char c = client.read();
    if(val.length() <= 20){
        val.concat(c);   
      } 
    Serial.print(val);
  }
  
  // if the server's disconnected, stop the client:
  if (!client.connected()) {
    Serial.println();
    Serial.println("disconnecting.");
    client.stop();

    // do nothing forevermore:
    while (true);
  }
}

Please anyone help me to solve this problem..

2

Now i want to save the text in the HTML body tag to string..Like below,

OK, you can save the data in a string. But, NOT like below. That assigns the data to a String, which is NOT the same as a string.

String readString = String(100);

That is equivalent to :

String readString = "100";

How is THAT a useful initial value?

  if (client.available()) {
    char c = client.read();
    if(val.length() <= 20){
        val.concat(c);   
      }
    Serial.print(val);
  }

If you KNOW how many characters to expect, there is NO reason to piss away memory using a String. Use a NULL terminated array of chars, instead.

Please anyone help me to solve this problem..

Sure thing. What IS the problem? You've collected at most 20 characters from the server's response, meaning that if the server responded ONLY with the data you showed above, val would contain "CRLF<ht". The data of interest isn't even in val, so extracting anything useful from val is not going to happen.

3

PaulS:
If you KNOW how many characters to expect, there is NO reason to piss away memory using a String. Use a NULL terminated array of chars, instead.
Sure thing. What IS the problem? You've collected at most 20 characters from the server's response, meaning that if the server responded ONLY with the data you showed above, val would contain "CRLF<ht". The data of interest isn't even in val, so extracting anything useful from val is not going to happen.

I'm very new to the arduino programming. if you can provide the sample code, I really appreciate it. because I dont understand how to do it..
Thanks

4

because I dont understand how to do it..

You are already collecting data into a String. Just not enough data. So, change the 20 character limit to something that ensures that you get all the data (or remove the limit, altogether, and collect the entire server response).

The portion of interest follows the 1st sequence of and ends with the beginning of the next sequence of .

The String class has an indexOf() method that would let you find the tag (and get past it). You could find the tag, to know where the data of interest ends.

Then, use trim() to get rid of the carriage returns, line feeds, and spaces at the beginning and end of the substring between the > at the end of the tag and the < at the start of the tag.

What are you going to do with that string?

5

PaulS:
What are you going to do with that string?

It's a very valid question.
Do you really wanted to do all the string parsing to get some values? Instead a small REST service can return a value you really wanted, then Arduino can use it without any string parsing.
Some one else can give some more insights, if you could tell some details of your project.

6

PaulS:
What are you going to do with that string?

I''m trying to get data from mysql database of my website.. in my web site has get.php web page.. which is used to retrieve the data from database and display it between their body tag. after that the aruino read the web page and write this value to output pin..

I'm doing this small project for exhibition of my school. please suggest any easy method with code.. because I haven't enough time.. the exhibition is start tomorrow morning.. please any one help me..

7

PaulS:
What are you going to do with that string?

Please please if you know how to do that please provide sample code for me..

8

after that the aruino read the web page and write this value to output pin..

So, you want to do something like

digitalWrite(somePin, "1,0,1,0,255,236,28,20");

You don't really expect that to work, do you?

Please please if you know how to do that please provide sample code for me..

To do what? You have not explained what you want to do. Getting the Arduino to collect the server output into a String is easy - you already have code to do that. The only problem with that code is that you have a useless limit to the length of the String incorporated. Get rid of that - it's a matter of deleting one line of code.

The next step is to extract the relevant data from the server response, and I already explained how to do that.

The last step is to do something with the relevant data, and you have waved your arms and made some silly statements about how you will use the data that are not useful for writing any code.