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c++unsigned-integer

Best practice for checking for no index for an unsigned integer

Say I have this function:

void doThings(uint8_t index) {
   if (an index is given) { ... }
}

Usually, an invalid index is -1, so that if statement would be if (index != -1). What if I'm using an unsigned integer to represent the index? Would it be silly to change the function definition to a signed int, just so I can test for -1? Is there a universally accepted number representing 'no index' for unsigned ints?

Solution

  • If you must take into account the two situations in the same function, a better option may be to just provide a second parameter.

    void doThings(uint8_t index, bool indexGiven) {
   if (indexGiven) { ... }
}

    However, using two entirely different functions, one for when the index is given and one for when it is not, may lead to a cleaner design.