unsigned int


Unsigned ints (unsigned integers) are the same as ints in that they store a 2 byte value. Instead of storing negative numbers however they only store positive values, yielding a useful range of 0 to 65,535 (2^16) – 1).

The difference between unsigned ints and (signed) ints, lies in the way the highest bit, sometimes referred to as the “sign” bit, is interpreted. In the Arduino  int type (which is signed), if the high bit is a “1”, the number is interpreted as a negative number, and the other 15 bits are interpreted with 2’s complement math.



    unsigned int ledPin = 13;



     unsigned int var = val;
  • var – your unsigned int variable name
  • val – the value you assign to that variable


Coding Tip

When variables are made to exceed their maximum capacity they “roll over” back to their minimum capacity, note that this happens in both directions

   unsigned int x
   x = 0;
   x = x - 1;       // x now contains 65535 - rolls over in neg direction
   x = x + 1;       // x now contains 0 - rolls over


See Also


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