parsing s serial string

[andywatson]

I have an Uno using MySoftSerial to receive a string of numbers on one of the Uno's digital input pins. The serial data is coming from a sensor connected to the Uno, and the sensor outputs a string once a minute in the following format: "234 93 242x" and is followed by a carriage return. I want to separate the string into the 3 integers that are space delimited, throwing away anything that is not an integer(the last character or two), then I want to store the ints so I can do some math and then write them to external memory.

I'm having trouble figuring out how to parse out the individual numbers from serial string. Can someone point me in the right direction? Thanks.

[tastewar]

I suspect sscanf would work for you...

http://www.nongnu.org/avr-libc/user-man ... fd8f5dca6f

[smindinvern]

this should do:

Code: Select all

#include <stdio.h>
#include <errno.h>

{
        char *input = "234 93 242x\r";        // just an example, fill this from the serial input
        char *nptr, *endptr = input;
        long int values[3];
        int i;

        for (i = 0; i < 3; i++) {
                values[i] = strtol(nptr, &endptr, 10);
                if (!endptr || endptr == nptr || errno == ERANGE)
                        return -1;        // error
        }
}

[fat16lib]

Here is a C++ extractor that can parse this string.

This sample sketch parses the string and prints the result:

Code: Select all

#include <SdFat.h>
// test string
char buf[] = "234 93 242x\r";

void setup() {
  int i, j, k;
  Serial.begin(9600); 
  // create an input buffer stream
  ibufstream ib(buf);
  // parse line with three ints and test for errors
  if (ib >> i >> j >> k) {
    // print result for success
    Serial.println(i);
    Serial.println(j);
    Serial.println(k);
  } else {
    //  process error
    Serial.println("error");
  }
}
void loop() {}

The new version of SdFat has C++ extraction operators, >>, and insertion operators, <<, for parsing and formatting strings in memory and files.

The beta is here http://code.google.com/p/beta-lib/downloads/list