warning: comparison of unsigned expression >= 0 is always true

Question

I have the following error when compiling a C file:

t_memmove.c: In function ‘ft_memmove’:
ft_memmove.c:19: warning: comparison of unsigned expression >=          


        

Answer 1

According to section 6.3.1.8 of the draft C99 standard Usual arithmetic conversions, since they are both of the same type, the result will also be size_t. The section states:

[...]Unless explicitly stated otherwise, the common real type is also the corresponding real type of the result[...]

and later on says:

If both operands have the same type, then no further conversion is needed.

mathematically you can just move the i over to the other side of the expression like so:

 n >= i