accessing websites using ethernet and finding strings

Projects Programming
1

Hello Guys! I am trying to access a wordpress website and find a particular string on the website. However, I can't connect to any website, other than google.com. Any help on finding the string and on accessing website would be apperciated.

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

/* configure address and server */
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };

/* website to access */
char server[] = "www.google.com";

/* to set static IP address: example*/
//IPAddress ip(192,168,0,177);

boolean powerOns = false;
const int powerPin = A0; // pin on arduino 
const int ledPin = 13;  // indication

int result; // the number

//char strData[32];
//int stringPos = 0;
boolean startRead = false;

// initialize Ethernet client library
EthernetClient client;

// set up environment 
void setup()
{
	Serial.begin(9600); // serial data transmission rate
        
        delay(1000);
        
	if(Ethernet.begin(mac) == 0)
	{
		Serial.println("Failed to connect");
	}

	// if connected; port 80 is default for HTTP
	if(client.connect(server,80))
	{
		Serial.println("connected");

	}




}

// run repeatedly 
void loop()
{
  if(client.connected() )
  {
    Serial.println("d");
    //Serial.println("availible");
    char c = client.read();
    if(c == 'g')  
    {
      Serial.println("z");   
    }

    client.stop();
    client.flush();   
   
  }

  if(!client.connected())  
   {
      client.stop();
    }




} // end of loop
2

where in your code, are you trying to connect to any website ?

3 
 	// if connected; port 80 is default for HTTP
	if(client.connect(server,80))
	{
		Serial.println("connected");

	}




}

// run repeatedly 
void loop()
{
  if(client.connected() )
  {

I access the website by connecting it; did I do it right?

4

All you do is connect, you don't issue any type of http command.

5

What do you mean? I wanted to know if I am connecting it right.
This is what I have after. I want to read the text on the website and find the letter g

// run repeatedly 
void loop()
{
  if(client.connected() )
  {
    Serial.println("d");
    //Serial.println("availible");
    char c = client.read();
    if(c == 'g')  
    {
      Serial.println("z");   
    }

    client.stop();
    client.flush();   
   
  }

  if(!client.connected())  
   {
      client.stop();
    }




}
6

Code that downloads weather data and displays it in the serial monitor.

// Include description files for other libraries used (if any)
#include <SPI.h>
#include <Ethernet.h>

// Define Constants
// Max string length may have to be adjusted depending on data to be extracted
#define MAX_STRING_LEN  20

// Setup vars
char tagStr[MAX_STRING_LEN] = "";
char dataStr[MAX_STRING_LEN] = "";
char tmpStr[MAX_STRING_LEN] = "";
char endTag[3] = {'<', '/', '\0'};
int len;

// Flags to differentiate XML tags from document elements (ie. data)
boolean tagFlag = false;
boolean dataFlag = false;

// Ethernet vars
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
byte ip[] = { 192, 168, 1, 102 };
byte server[] = { 140, 90, 113, 200 }; // www.weather.gov

// Start ethernet client
EthernetClient client;

void setup()
{
  Serial.begin(9600);
  Serial.println("Starting WebWx");
  Serial.println("connecting...");
  Ethernet.begin(mac, ip);
  delay(1000);

  if (client.connect(server, 80)) {
    Serial.println("connected");
    client.println("GET /xml/current_obs/KRDU.xml HTTP/1.0");    
    client.println();
    delay(2000);
  } else {
    Serial.println("connection failed");
  }  
}

void loop() {

  // Read serial data in from web:
  while (client.available()) {
    serialEvent();
  }

  if (!client.connected()) {
    Serial.println();
    Serial.println("Disconnected");
    Serial.println("==================================");
    Serial.println("");
    client.stop();

    // Time until next update
    //Serial.println("Waiting");
    for (int t = 1; t <= 15; t++) {
      delay(60000); // 1 minute
    }

    if (client.connect(server, 80)) {
      //Serial.println("Reconnected");
      client.println("GET /xml/current_obs/KRDU.xml HTTP/1.0");    
      client.println();
      delay(2000);
    } else {
      Serial.println("Reconnect failed");
    }      
  }
}

// Process each char from web
void serialEvent() {

   // Read a char
	 char inChar = client.read();
   //Serial.print(".");
  
   if (inChar == '<') {
      addChar(inChar, tmpStr);
      tagFlag = true;
      dataFlag = false;

   } else if (inChar == '>') {
      addChar(inChar, tmpStr);

      if (tagFlag) {      
         strncpy(tagStr, tmpStr, strlen(tmpStr)+1);
      }

      // Clear tmp
      clearStr(tmpStr);

      tagFlag = false;
      dataFlag = true;      
      
   } else if (inChar != 10) {
      if (tagFlag) {
         // Add tag char to string
         addChar(inChar, tmpStr);

         // Check for </XML> end tag, ignore it
         if ( tagFlag && strcmp(tmpStr, endTag) == 0 ) {
            clearStr(tmpStr);
            tagFlag = false;
            dataFlag = false;
         }
      }
      
      if (dataFlag) {
         // Add data char to string
         addChar(inChar, dataStr);
      }
   }  
  
   // If a LF, process the line
   if (inChar == 10 ) {

/*
      Serial.print("tagStr: ");
      Serial.println(tagStr);
      Serial.print("dataStr: ");
      Serial.println(dataStr);
*/

      // Find specific tags and print data
      if (matchTag("<temp_f>")) {
	      Serial.print("Temp: ");
         Serial.print(dataStr);
      }
      if (matchTag("<relative_humidity>")) {
	      Serial.print(", Humidity: ");
         Serial.print(dataStr);
      }
      if (matchTag("<pressure_in>")) {
	      Serial.print(", Pressure: ");
         Serial.print(dataStr);
         Serial.println("");
      }

      // Clear all strings
      clearStr(tmpStr);
      clearStr(tagStr);
      clearStr(dataStr);

      // Clear Flags
      tagFlag = false;
      dataFlag = false;
   }
}

/////////////////////
// Other Functions //
/////////////////////

// Function to clear a string
void clearStr (char* str) {
   int len = strlen(str);
   for (int c = 0; c < len; c++) {
      str[c] = 0;
   }
}

//Function to add a char to a string and check its length
void addChar (char ch, char* str) {
   char *tagMsg  = "<TRUNCATED_TAG>";
   char *dataMsg = "-TRUNCATED_DATA-";

   // Check the max size of the string to make sure it doesn't grow too
   // big.  If string is beyond MAX_STRING_LEN assume it is unimportant
   // and replace it with a warning message.
   if (strlen(str) > MAX_STRING_LEN - 2) {
      if (tagFlag) {
         clearStr(tagStr);
         strcpy(tagStr,tagMsg);
      }
      if (dataFlag) {
         clearStr(dataStr);
         strcpy(dataStr,dataMsg);
      }

      // Clear the temp buffer and flags to stop current processing
      clearStr(tmpStr);
      tagFlag = false;
      dataFlag = false;

   } else {
      // Add char to string
      str[strlen(str)] = ch;
   }
}

// Function to check the current tag for a specific string
boolean matchTag (char* searchTag) {
   if ( strcmp(tagStr, searchTag) == 0 ) {
      return true;
   } else {
      return false;
   }
}
7

You normally have to connect to your own router or gateway or modem first, and then to the internet.

If you look at zoomkat's example, that is what he is doing, and you are not.

8

frostkarrotor:
What do you mean? I wanted to know if I am connecting it right.
This is what I have after. I want to read the text on the website and find the letter g

// run repeatedly

void loop()
{
  if(client.connected() )
  {
    Serial.println("d");
    //Serial.println("availible");
    char c = client.read();
    if(c == 'g') 
    {
      Serial.println("z");   
    }

client.stop();
    client.flush();   
   
  }

if(!client.connected()) 
   {
      client.stop();
    }

}

I mean that the library you're using doesn't include the http stack, so you'll actually need to issue the request to get the page. Just connecting over TCP isn't enough.