# FLT_EVAL_METHOD

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< c‎ | types‎ | limits

Defined in header ``<float.h>`` |  |
#define FLT_EVAL_METHOD /* implementation-defined */ |  | (since C99)

Specifies range and precision of floating-point values obtained from floating-point constants and from all operations (operators, implicit conversions of operands) except assignment, cast, and library function call.

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

### Notes

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.

### See also

float_t (C99) | most efficient floating-point type at least as wide as float (typedef)
double_t (C99) | most efficient floating-point type at least as wide as double (typedef)
C++ documentation for FLT_EVAL_METHOD

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