CGFloat: round, floor, abs, and 32/64 bit precision

Question

TLDR: How do I call standard floating point code in a way that compiles both 32 and 64 bit CGFloats without warnings?

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CGFloat is defined as either double or float, depending on the compiler settings and platform. I'm trying to write code that works well in both situations, without generating a lot of warnings.

When I use functions like floor, abs, ceil, and other simple floating point operations, I get warnings about values being truncated. For example:

warning: implicit conversion shortens 64-bit value into a 32-bit value

I'm not concerned about correctness or loss of precision in of calculations, as I realize that I could just use the double precision versions of all functions all of the time (floor instead of floorf, etc); however, I would have to tolerate these errors.

Is there a way to write code cleanly that supports both 32 bit and 64 bit floats without having to either use a lot of #ifdef __ LP64 __ 's, or write wrapper functions for all of the standard floating point functions?

Phira

Answer 1

You may use those functions from tgmath.h.

#include <tgmath.h>

...

double d = 1.5;
double e = floor(d);   // will choose the 64-bit version of 'floor'

float f = 1.5f;
float g = floor(f);    // will choose the 32-bit version of 'floorf'.

Sea

Now that I know what to search for, I found this question: #5352957 – Phira

Note that in Xcode 6.1, including tgmath doesn't help if modules are enabled. See https://mcmap.net/q/131226/-tgmath-h-doesn-39-t-work-if-modules-are-enabled/449161 – Stadia

Answer 2

If you only need a few functions you can use this instead:

#if CGFLOAT_IS_DOUBLE
#define roundCGFloat(x) round(x)
#define floorCGFloat(x) floor(x)
#define ceilCGFloat(x) ceil(x)
#else
#define roundCGFloat(x) roundf(x)
#define floorCGFloat(x) floorf(x)
#define ceilCGFloat(x) ceilf(x)
#endif

Brettbretz