Convert int to char[]
itoa is the best route:

int num = 1234;
char cstr[16];
itoa(num, cstr, 10);
-&gt; "1234"


You can read more about using it here.

If you want more control over the format of the number (and don't mind the increased PROGMEM usage) you can use sprintf (or the more secure snprintf) to format it:

sprintf(cstr, "%05d", num);
-&gt; "01234"


Or with PROGMEM string constant:

sprintf_P(cstr, (PGM_P)F("%05d"), num);
-&gt; "01234"


Or with more values:

sprintf_P(cstr, (PGM_P)F("%02d:%02d:%02d"), hours, minutes, seconds);
-&gt; "03:23:11"