Causes of periodic failure in parsing data passed in HTTP GET requests?

i'm doing , http sends /?roundlevel=x arduino ethernet shield. please note, x value hard-coded in there, can simple

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if(readstring.indexof("roundlevel=0")>0) tests. arduino running web server sketch. have if statements set in sketch execute code when x = 0, 2 or 3. it's unreliable. when x 0 or 2, arduino 'sees' , executes code in if statement. never suceeds when x = 3. not sure whether problem 1) can't read 3, or 2)this timing issue, or 3) fails read sending in after number of requests. typically (although not always), x=3 on 7th get. there reason might fail after 7th request? requests same client , can happen rapidly within 3 seconds of 1 another. 
i can't seem debug issue using serial.print() because (for reasons don't understand) serial.begin(9600) interferes arduino-as-server's ability accept client requests. suggestions?  code below.

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#include <spi.h>
#include <ethernet.h>n

//ethernet shield's mac address
byte mac[] = { 0x90, 0xa2, 0xda, 0x00, 0xf7, 0x99 };
//ip address assigned network
ipaddress ip(10,132,7,115);
// router's gateway address
byte gateway[] = { 10, 132, 7, 254 };
//// subnet:
byte subnet[] = { 255, 255, 254, 0 };

ethernetserver server(80);

string roundopentag = "<game>";
string roundclosetag = "</game>";
long randnumber;
string ledcolor = "";
int seqarray[5] = {3,5,6,7,8};
int loops = 5;
string readstring = string(100);

void setup()
{
  pinmode(8, output);
  pinmode(7, output);
  pinmode(6, output);
  pinmode(5, output);
  pinmode(3, output);
  ethernet.begin(mac, ip);
  server.begin();
}

void loop()
{
  // listen incoming clients
  ethernetclient client = server.available();
  if (client)
    {
      boolean currentlineisblank = true;
      while (client.connected())
        {
          if (client.available())
            {
              //if there request,
              //read request
              char c = client.read();
       
              //store characters string
               readstring +=c;
       
              if(readstring.indexof("roundlevel=0")>0)
              {
               roundopentag = "<one>";
               roundclosetag = "</one>";
              }
              if(readstring.indexof("roundlevel=2")>0)
              {
               roundopentag = "<two>";
               roundclosetag = "</two>";
               loops = 6;
              }
              if(readstring.indexof("roundlevel=3")>0)
              {
               roundopentag = "<three>";
               roundclosetag = "</three>";
               loops = 7;
              }
       
         // if you've gotten end of line (received newline
        // character) , line blank, http request has ended,
        // can send reply
              if (c == '\n' && currentlineisblank)
              {
              // send standard http response header
                client.println("http/1.1 200 ok");
                client.println("content-type: text/html");
                client.println();
                //this delay gives player second phone
                //to blinky
                delay(1000);
                (int = 0; < loops; i++)
                {
                  //pull randomn number between 0 , 4
                  randomseed(analogread(1));
                  randnumber = random(0, 5);
                 
                  if (randnumber == 0)
                  {
                     ledcolor = "red";
                  }
                  else if (randnumber == 1)
                  {
                      ledcolor = "orange";
                  }
                   else if (randnumber == 2)
                  {
                      ledcolor = "yellow";
                  }
                   else if (randnumber == 3)
                  {
                      ledcolor = "green";
                  }
                   else
                  {
                      ledcolor = "blue";
                  }
                  digitalwrite(seqarray[randnumber], high);
                  // set led on 1/4 second
                  delay(250);
                 
                  //write xml open tag
                  client.print(roundopentag);
                  //write xml text (light color)
                  client.print(ledcolor + "<br />");
                 
                  digitalwrite(seqarray[randnumber], low);
                  //set led off 1/2 second
                  delay(250);
                 
                  //write xml closed tag
                  client.print(roundclosetag);
                  }
                  break;
              }
              if (c == '\n')
              {
                // you're starting new line
                currentlineisblank = true;
              }
              else if (c != '\r')
              {
                // you've gotten character on current line
                currentlineisblank = false;
              }
            }
        }
    // give web browser time receive data
    delay(1);
    // close connection:
    client.stop();
  }
}

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string readstring = string(100);
what think doing?

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                  randomseed(analogread(1));
should done once in setup(), not every time need random number.

quote

i can't seem debug issue using serial.print() because (for reasons don't understand) serial.begin(9600) interferes arduino-as-server's ability accept client requests. suggestions?  code below.

not me, doesn't.

personally, i'd ditch string class. making far liberal use of class, unnecessarily. creating char pointers pointing "red", "green", etc, , char pointer, ledcolor, points appropriate color name, rather dynamically assigning colors save bunch of memory. ditto open , close tags.

it easy store client request data in array, rather string object, , use pointers point parts of request, strcmp() purposes, instance. doing allow rid of string class , memory fragmenting going on.

Arduino Forum > Using Arduino > Networking, Protocols, and Devices (Moderator: fabioc84) > Causes of periodic failure in parsing data passed in HTTP GET requests?

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