Delate something in a string.

Projects Programming
1

Hello, I wanted to build a network to i²c converter.

But the strings are too long so I wanted to make them smaller.

         int spacePosition = readString.indexOf('/');
          if (readString.charAt(spacePosition + 1) == '?') 
          {
            Wire.beginTransmission(4); // transmit to device #4
            char buffer[32];
            readString.toCharArray(buffer, 32);
            Wire.write(buffer);
            Serial.print(buffer);
            Wire.endTransmission();    // stop transmitting
           }

the strings are

GET /?lighton0 HTTP/1.1
GET /favicon.ico HTTP/1.1

I have successfully deleted the favicon string.
and the second string I wanted to reduce that only remains 'lighton0'

sorry for my bad english, but im a german :smiley:

can anyone help me ?
Thanks for answer.

2

Please post your whole program so that your question can be seen in the context in which it is asked.

3

i think the rest isn't interesting but here...

#include <SPI.h>
#include <Ethernet.h>
#include <Wire.h>
byte mac[] = {0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED }; //physical mac address
byte ip[] = {192, 168, 0, 5 }; // ip in lan
EthernetServer server(80); //server port
String readString; 
void setup()
{
  Ethernet.begin(mac, ip);
  server.begin();
  Serial.begin(9600); 
  Serial.print("server is at ");
  Serial.println(Ethernet.localIP());
  Wire.begin(); // join i2c bus (address optional for master)
}
void loop()
{
  EthernetClient client = server.available();
  if (client) 
  {
    while (client.connected()) 
    {
      if (client.available()) 
      {
        char c = client.read();
        if (readString.length() < 100) readString += c; 
        if (c == '\n') 
        {
          client.stop();
          int spacePosition = readString.indexOf('/');
          if (readString.charAt(spacePosition + 1) == '?') 
          {
            Wire.beginTransmission(4); // transmit to device #4
            char buffer[32];
            readString.toCharArray(buffer, 32);
            Wire.write(buffer);
            Serial.print(buffer);
            Wire.endTransmission();    // stop transmitting
           }
           readString="";
        }
      }
    }
  }
}

#include <Wire.h>
void setup()
{
  Wire.begin(4);              
  Wire.onReceive(receiveEvent);
  Serial.begin(9600);           
}
void loop()
{
  delay(100);
}
void receiveEvent(int howMany)
{
  while(1 < Wire.available()) // loop through all but the last
  {
    char c = Wire.read(); // receive byte as a character
    Serial.print(c);         // print the character
  }
  int x = Wire.read();    // receive byte as an integer
  Serial.println(x);         // print the integer
}
4

Can you give an example of a string that is too long and what you want to reduce it to ?

5

"GET /?lighton0 HTTP/1.1" is the tring but i just need "lighton0"

6

You are using the String class, despite the issues that it presents. The class has indexOf() and substring() methods. You can look up how to use them.

7 
          int firstPosition = readString.indexOf('/');
          if (readString.charAt(firstPosition + 1) == '?')
          {
            int secountPosition = readString.indexOf(' ',firstPosition+2);
            tempString = readString.substring(firstPosition+2,secountPosition);
            Wire.beginTransmission(4); // transmit to device #4
            char buffer[32];
            tempString.toCharArray(buffer, 32);
            Wire.write(buffer);
            Serial.println(buffer);
            Wire.endTransmission();    // stop transmitting
           }

it work thank you :slight_smile:

8 
          int firstPosition = readString.indexOf('/');
          if (readString.charAt(firstPosition + 1) == '?')
          {
            int secountPosition = readString.indexOf(' ',firstPosition+2);

Wouldn't slashPosition and spacePosition make more sense as the names?