Char substring, not String substring

[J-M-L]

if you want to go a small bit faster esp if your buffer is long (no need to put null characters everywhere in the buffer to override them just later and just really need one at the end

  char myChar[] {"123456789"};
  byte numberOfBytesOfInterest = 2;
  char subString[numberOfBytesOfInterest+1] ;
  strlcpy(subString, myChar+4, sizeof subString); // strlcpy will also ensure you don't overrun the buffer