Defined in header <cfloat> | ||
|---|---|---|
#define FLT_EVAL_METHOD /* implementation defined */ | (since C++11) |
Specifies the precision in which all floating-point arithmetic operations other than assignment and cast are done.
| Value | Explanation |
|---|---|
negative values except -1 | implementation-defined behavior |
-1 | the default precision is not known |
0 | all operations and constants evaluate in the range and precision of the type used. Additionally, float_t and double_t are equivalent to float and double respectively |
1 | all operations and constants evaluate in the range and precision of double. Additionally, both float_t and double_t are equivalent to double |
2 | all operations and constants evaluate in the range and precision of long double. Additionally, both float_t and double_t are equivalent to long double |
Regardless of the value of FLT_EVAL_METHOD, any floating-point expression may be contracted, that is, calculated as if all intermediate results have infinite range and precision (unless #pragma STDC FP_CONTRACT is off).
Cast and assignment strip away any extraneous range and precision: this models the action of storing a value from an extended-precision FPU register into a standard-sized memory location.
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