float_t, double_t

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< c ‎ | numeric ‎ | math
Common mathematical functions
Types
float_t double_t
(C99) (C99)

Functions
Basic operations
(C99)
(C99)
(C99)
(C99) (C99) (C99) (C23)
Maximum/minimum operations
Exponential functions
Power functions
Trigonometric and hyperbolic functions
Error and gamma functions
(C99)
(C99)
(C99)
(C99)
Nearest integer floating-point operations
(C99) (C99) (C99)
(C23) (C23) (C23) (C23)
Floating-point manipulation functions
Narrowing operations
(C23)
(C23)
(C23)
(C23)
(C23)
(C23)
Quantum and quantum exponent functions
Decimal re-encoding functions
Total order and payload functions
Classification
Macro constants
Special floating-point values
Arguments and return values
Error handling
Defined in header <math.h>
typedef /*implementation defined*/ float_t
(since C99)
typedef /*implementation defined*/ double_t
(since C99)

The types float_t and double_t are floating types at least as wide as float and double , respectively, and such that double_t is at least as wide as float_t . The value of FLT_EVAL_METHOD determines the types of float_t and double_t .

FLT_EVAL_METHOD Explanation
0 float_t and double_t are equivalent to float and double , respectively
1 both float_t and double_t are equivalent to double
2 both float_t and double_t are equivalent to long double
other both float_t and double_t are implementation defined

Example

#include <float.h>
#include <math.h>
#include <stdio.h>
 
int main(void)
{
    printf("%d\n", FLT_EVAL_METHOD);
    printf("%zu  %zu\n", sizeof(float),sizeof(float_t));
    printf("%zu  %zu\n", sizeof(double),sizeof(double_t));
    return 0;
}

Possible output:

0
4  4
8  8

References

  • C11 standard (ISO/IEC 9899:2011):
  • 7.12 Mathematics <math.h> (p: 231)
  • C99 standard (ISO/IEC 9899:1999):
  • 7.12 Mathematics <math.h> (p: 212)


See also

use of extended precision for intermediate results: 0 not used, 1 double is used instead of float , 2: long double is used
(macro constant)