Hex numbers in String format

Projects Programming
1

Hi...i hope someone could help me on this:

I have (coming on serial port) this string: "0002003A001100100008000D00020000"...this represents hex numbers like: 0002-003A-0011-0010-0008-000D-0002-10A3 in Hex ( 2-58-17-16-8-13-2-4529 in Decimal )...so I'm reading this entire string in a char array like charBufer[50] so each place on the buffer holds one ascii of the string.....the big question...how can I convert this entire string in a way that I can store the result of each Hex number in lets say another buffer like intBuffer[8]?...thanks in advance for your help

2

You have to chop that string up into pieces then call atoi() strtol() each piece.

You can do this after you receive the entire string or 4 bytes at a time while you are receiving.

Rob

3

Here's a small example program, there's probably a shorter way but this is the first thing I thought of.

#define NUMBER_OF_VALUES 8
#define NUMBER_OF_CHARS (NUMBER_OF_VALUES * 4)
int intBuffer[NUMBER_OF_VALUES];

byte charBuffer[NUMBER_OF_CHARS +1] = {"0002003A001100100008000D00020000"};
char x[5] = {0,0,0,0,0};

void setup() {

  Serial.begin(115200);

  for (int i = 0, v = 0; i < NUMBER_OF_CHARS; ) {
    x[0] = charBuffer[i++];
    x[1] = charBuffer[i++];
    x[2] = charBuffer[i++];
    x[3] = charBuffer[i++];
    intBuffer[v++] = (byte)strtol(x,NULL,16);
  }
  for (int i = 0; i < NUMBER_OF_VALUES; i++) {
    Serial.println ( intBuffer[i], HEX);
  }
}

void loop() {

}

Rob

4

I'd be strongly tempted to change

    x[0] = charBuffer[i++];
    x[1] = charBuffer[i++];
    x[2] = charBuffer[i++];
    x[3] = charBuffer[i++];

to

    for (byte j = 0 ; j < 4 ; j++)
      x[j] = charBuffer[i++];
  • but then I'd also probably program the hex conversion directly rather than call atoi() :slight_smile: