Unsigned int reverse iteration with for loops

Question

I want the iterator variable in a for loop to reverse iterate to 0 as an unsigned int, and I cannot think of a similar comparison to i > -1, as

Answer 1

The following does what you want:

for (unsigned i = 10; i != static_cast(-1); --i)
{
    // ...
}

This is perfectly defined and actually works. Arithmetic on signed types is accurately defined by the standard. Indeed:

From 4.7/2 (regarding casting to an unsigned type):

If the destination type is unsigned, the resulting value is the least unsigned integer congruent to the source integer (modulo 2^n where n is the number of bits used to represent the unsigned type)

and 3.9.1/4

Unsigned integers, declared unsigned, shall obey the laws of arithmetic modulo 2^n where n is the number of bits in the value representation of that particular size of integer