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float_t, double_t

most efficient floating types

Math library (libm)

#include <math.h>
typedef /* ... */ float_t;
typedef /* ... */ double_t;

The implementation's most efficient floating types at least as wide as float and double respectively. Their type depends on the value of the macro FLT_EVAL_METHOD (defined in <float.h>):

FLT_EVAL_METHOD float_t double_t
0 float double
1 double double
2 long double long double

For other values of FLT_EVAL_METHOD, the types of float_t and double_t are implementation-defined.

C11, POSIX.1-2008.

C99, POSIX.1-2001.

float.h(0p), math.h(0p)