I need to print mentioned below byte array on the serial monitor screen of Arduino IDE

char b[]= {'0x7E', '0x00', '0x1C','0x90', '0x00', '0x13', '0XA2', '0x00', '0x41', '0x58', '0x1C', '0xCB', '0xFF', '0xFE', '0xC1', '0x7C', '0x00','0x0F', '0x00', '0x01', '0x00', '0x00', '0x37', '0x46', '0x46', '0x46', '0x00', '0x00', '0x00', '0xE7' };
void setup() {

void loop() {

But whenever I am trying a print, the error problem was there which was not resolved which is

C:\Users\Misha\Desktop\test\Test_2\Test_2.ino: In function 'void loop()':

Test_2:8:18: error: expected primary-expression before ']' token



exit status 1
expected primary-expression before ']' token

Any suggestions on this will be great help.

  • what is b[]? array variable is simply b. – Juraj Jan 22 '19 at 7:59
  • Hey, Thanks for the suggestion whenever I have used Serial.println(b) also but its printing only the LSB value, I am not able to print the MSB values. – varul jain Jan 22 '19 at 8:05
  • of course. you can't print an array with print and invalid syntax will not help with it – Juraj Jan 22 '19 at 8:08
  • What MSB values are you on about? You just have a list of 8 bit values. There is nothing "MSB" or "LSB" about them. I think you need to go back and rethink what it is you are doing and asking and get the two to match up. – Majenko Jan 22 '19 at 10:59

You can’t print an array in that way.

If you want to print an array of hexadecimal value (with two digits), you have to use sprintf function and change declaration of b array.

uint8_t b[]= {0x7E, 0x00, 0x1C, 0x90, 0x00, 0x13, 0XA2, 0x00, 
              0x41, 0x58, 0x1C, 0xCB, 0xFF, 0xFE, 0xC1, 0x7C, 
              0x00, 0x0F, 0x00, 0x01, 0x00, 0x00, 0x37, 0x46, 
              0x46, 0x46, 0x00, 0x00, 0x00, 0xE7};
int i;

void printHex(uint8_t num) {
  char hexCar[2];

  sprintf(hexCar, "%02X", num);

void setup() {

void loop() {
  for(i=0; i<sizeof(b); i++){


The output produced is:

7E001C900013A20041581CCBFFFEC17C000F0001000037464646000000E7 7E001C900013A20041581CCBFFFEC17C000F0001000037464646000000E7 7E001C900013A20041581CCBFFFEC17C000F0001000037464646000000E7

  • Similar in this case It only displays the LSB values but no MSB values were displayed in serial monitor screen – varul jain Jan 22 '19 at 8:06
  • What do you want to print? ASCII character or the hex value? In serial monitor Do you want this: 7E 00 ... ? – leoc7 Jan 22 '19 at 8:33
  • @varuljain I updated the answer. – leoc7 Jan 22 '19 at 9:14
  • Btw the buffer is too small to contain two characters and '\0' character. – KIIV Jan 22 '19 at 9:29
  • I am anxious to understand HOW to use the Serial Monitor – martymarty Jan 8 '20 at 18:44

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