Converting (char*)variable to int

Question

I have the following code:

      uint8_t buf[1];
      uint8_t buflen = 1;
      if (driver.recv(buf, &buflen)) // Non-blocking
         {
            int i;
            // Message with a good checksum received, dump it.
            Serial.print("Message: ");
            Serial.println((char*)buf);//this prints out okay
            highPins[(char*)buf] = 1;
         }

The problem is in highPins[(char*)buf]. highPins is array, and in (char*)buf I get index number. When I display it with Serial.println, it shows the number, but here it does not. I am guessing its because (char*)buf is not a number. I have tried to convert it to int with few functions I have found online, but it was unsuccessful. Any help is appreciated :)

Answer 1

I would suggest improving your code slightly as follows:

  uint8_t buf;
  uint8_t buflen = 1;
  if (driver.recv(&buf, &buflen)) // Non-blocking
     {
        int i;
        // Message with a good checksum received, dump it.
        Serial.print("Message: ");
        Serial.println(buf);//this prints out okay
        highPins[buf] = 1;
     }

The important point is that you do not need to declare buf as an array of just one element, but just declare the element itself (as uint8_t) and pass its address (&buf) to driver.recv(...).

As @Majenko suggested, you should alos check buf before using it as an index to highPins array, in order to avoid using an index bigger than teh array size.

Answer 2

The function you want is atoi.

int pinno = atoi((char *)buf);

I would suggest checking that the result is in the right range before using it.