Unsigned int reverse iteration with for loops

c++ loops for-loop overflow iteration
deceleratedcaviar picture deceleratedcaviar · Mar 28, 2011 · Viewed 9.6k times · Source

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 you would do if it was a signed int. 

for (unsigned int i = 10; i <= 10; --i) { ... }

But this seems very unclear, as it is relying on the numerical overflow of the unsigned integer to be above 10.

Maybe I just don't have a clear head, but whats a better way to do this...

Disclaimer: this is just a simple use case, the upper limit of 10 is trivial, it could be anything, and i must be an unsigned int.

Answer

Serge Dundich picture Serge Dundich · Mar 28, 2011

You can use

for( unsigned int j = n; j-- > 0; ) { /*...*/ }

It iterates from n-1 down to 0.

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