C/C++ use of int or unsigned int

Using unsigned can introduce programming errors that are hard to spot, and it’s usually better to use signed int just to avoid them. One example would be when you decide to iterate backwards rather than forwards and write this:

for (unsigned i = 5; i >= 0; i--) {
    printf("%d\n", i);
}

Another would be if you do some math inside the loop:

for (unsigned i = 0; i < 10; i++) {
    for (unsigned j = 0; j < 10; j++) {
        if (i - j >= 4) printf("%d %d\n", i, j);
    }
}

Using unsigned introduces the potential for these sorts of bugs, and there’s not really any upside.