Absolute value function 'fabsf' given an argument of type 'double' but has parameter of type 'float' which may cause truncation of value?

Question

Given this code sample:

CGFloat a = 1;
CGFloat b = 2;
CGFloat c = fabsf(a-b);

The current Xcode beta compiler gives me this warning:

Absolute value function 'fabsf' given an argument of type 'double' but has parameter of type 'float' which may cause truncation of value

Why?

Answer 1

You can use fabs instead of fabsf.

Link

Answer 2

I see, the code works with a plain float type. And when I hunted for the definition of CGFloat, I found this:

#if defined(__LP64__) && __LP64__
# define CGFLOAT_TYPE double
# define CGFLOAT_IS_DOUBLE 1
# define CGFLOAT_MIN DBL_MIN
# define CGFLOAT_MAX DBL_MAX
#else
# define CGFLOAT_TYPE float
# define CGFLOAT_IS_DOUBLE 0
# define CGFLOAT_MIN FLT_MIN
# define CGFLOAT_MAX FLT_MAX
#endif

typedef CGFLOAT_TYPE CGFloat;

So CGFloat is now actually a double, hence the warning.