ARDUINO: Serial.print a multiple-character element

Question

I need to print 4-bit long numbers, these numbers are Binary numbers frome 0 to 16 (0000, 0001, 0010, ...).

PROBLEMS:

Considering this code:

char array[] = {'0000', '0001', '0010', '0011'};
int i;

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

void loop() {
  while (i < 4){
    Serial.println(array[i]);
    i++;
  }
}

The serial monitor outputs:

My expected output is:

It seems that only the first "character" of each element of the array is read.

QUESTION: How can I print the entirety of each element like in my expected output?

After some reasearch, I found this:

Arduino serial print

which then refers to using PROGMEM but I'm not sure if this is what I need or if there is a simpler solution to my problem.

Multi-character constants like e.g. '0000' are implementation-defined in how they work. Please don't use such. If you want multiple characters, use strings instead. — Some programmer dude
– Some programmer dude, Commented Nov 11, 2020 at 16:53
As for one of the problem with such constants, think about that on most systems (Arduino included) char is a single byte. How would you fit four characters into a single byte? — Some programmer dude
– Some programmer dude, Commented Nov 11, 2020 at 16:54
do you ignore sketch_nov11b.ino:1:17: warning: character constant too long for its type char array[] = {'0000', '0001', '0010', '0011'};? — Juraj
– Juraj, Commented Nov 11, 2020 at 18:44

ocrdu · Accepted Answer · 2022-07-25 08:29:29Z

1

As mentioned in the comments, don't use multi-character constants (the ones you used, with single quotes); they might kill puppies. Single quotes are for character constants, like 'a'.

You can use strings (with double quotes), or real binary numbers without trickery; the latter will print without leading zeros.

This code example does both, so pick what you need:

const char* array1[] = {"0000", "0001", "0010", "0011"}; // strings
uint8_t array2[] = {0b000, 0b0001, 0b0010, 0b0011};      // binary numbers
int arraySize = sizeof(array1) / sizeof(array1[0]);
    
void setup() {
  Serial.begin(9600);
  while (!Serial);
    
  Serial.println("Print the strings:");  
  int i = 0;
  while (i < arraySize){
    Serial.println(array1[i]);
    i++;
  }
      
  Serial.println("\nPrint the binary numbers (note: no leading zeroes):");
  i = 0;
  while (i < arraySize){
    Serial.println(array2[i], BIN);
    i++;
  }
      
}
    
void loop() {
}

edited Jul 25, 2022 at 8:29

answered Nov 11, 2020 at 18:39

ocrdu

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1 Comment

Polymood Over a year ago

It works, that's exactly what i needed, thank you for your help I didn't know it was possible to create an array of strings like you did

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