How to Serial.print unsigned char xxxx[] ?

Using Arduino Programming Questions
1

In my sketch I have this that stores serial numbers;

unsigned char login[][8] =
{
{0x12, 0x22, 0x71, 0x16, 0x13, 0x74, 0x00, 0x00},
{0x10, 0x42, 0x71, 0x11, 0x15, 0x36, 0x00, 0x00},
};

How do I Serial.print (login[i]) each serial number to the console?

so it would print it as either

0x12, 0x22, 0x71, 0x16, 0x13, 0x74, 0x00, 0x00

or

1222711613740000

2

with two nested for loops.

try something like this

unsigned char login[][8] = {
  {0x12, 0x22, 0x71, 0x16, 0x13, 0x74, 0x00, 0x00},
  {0x10, 0x42, 0x71, 0x11, 0x15, 0x36, 0x00, 0x00}
};

void setup() {
  Serial.begin(115200);

  for (int i = 0; i < sizeof login / sizeof * login; i++) {
    Serial.print("login["); Serial.print(i); Serial.print("] = {");
    for (int j = 0; j < sizeof login[0] / sizeof * login[0]; j++) {
      Serial.print("0x");  // Print the "0x" prefix
      if (login[i][j] < 0x10) Serial.write('0');
      Serial.print(login[i][j], HEX);
      if (j < 7) Serial.write(", ");
    }
    Serial.println("}");  // Print a newline after each serial number
  }
}

void loop() {}

you should see in the serial monitor (set at 115200 bauds)

login[0] = {0x12, 0x22, 0x71, 0x16, 0x13, 0x74, 0x00, 0x00}
login[1] = {0x10, 0x42, 0x71, 0x11, 0x15, 0x36, 0x00, 0x00}
1 Like
3 
void disp (
    unsigned char *buf,
    int            nByte )
{
    char s[10];

    sprintf (s, "0x%02x", buf [0]);
    Serial.print (s);

    for (int n = 1; n < nByte; n++) {
        sprintf (s, ", 0x%02x", buf [n]);
        Serial.print (s);
    }
    Serial.println (s);
}

unsigned char login[][8] = {
    {0x12, 0x22, 0x71, 0x16, 0x13, 0x74, 0x00, 0x00},
    {0x10, 0x42, 0x71, 0x11, 0x15, 0x36, 0x00, 0x00},
};

void
setup (void)
{
    Serial.begin (9600);

    disp (&login [1][0], 8);
    disp (&login [0][0], 8);
}

void loop (void) { }
1 Like
4

Thank you both for your help, that's fantastic.