CGFloat: round, floor, abs, and 32/64 bit precision
TLDR: How do I call standard floating point code in a way that compiles both 32 and 64 bit CGFloats without warnings?
CGFloat is defined as either double or float, depending on the compiler settings and platform. I'm try开发者_Python百科ing 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?
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'.
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
精彩评论