I am trying to find out the size of an array like this:

    String days[3] = { "Mon", "Tue", "Wed" };
Serial.printf("Size of array: %2d\n", sizeof(days));
for (int i = 0; i < sizeof(days); i++) {

The result of the code above is 36 which is incorrect.

Do I have any other options considering that I don't know the size of the array to begin with?

  • sizeof() is the number of bytes and not the number of elements. sizeof(array) / sizeof(element) gives the number of elements. Commented Jul 28, 2016 at 12:38

1 Answer 1


No, the result is correct, you're just interpreting it incorrectly. If you want the number of elements in a statically-allocated array use:

sizeof(somearray) / sizeof(somearray[0])
  • Sorry if I post in wrong topic follow answer of Ignacio Vazquez-Abrams, in case of size of each String in array is different? like String days[] = { "Monday", "Tuesday", "Wednesday" }; Thanks Commented Nov 14, 2016 at 6:53

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