Can't get rid of “this decimal constant is unsigned only in ISO C90” warning

Question

I\'m using the FNV hash as a hashing algorithm on my Hash Table implementation but I\'m getting the warning in the question title on this line:

unsigned hash         


        

Answer 1

unsigned hash = 2166136261u; // note the u.

You need a suffix u to signify this is an unsigned number. Without the u suffix it will be a signed number. Since

2166136261 > 2³¹ - 1 = INT_MAX,

this integer literal will be problematic.