float_t, double_t
From cppreference.com
| Defined in header <math.h>
|
||
typedef /* implementation-defined */ float_t
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(since C99) | |
typedef /* implementation-defined */ double_t
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(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
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Explanation |
0
|
float_t and double_t are equivalent to float and double, respectively
|
1
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both float_t and double_t are equivalent to double
|
2
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both float_t and double_t are equivalent to long double
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other
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both float_t and double_t are implementation defined
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Example
Run this code
#include <float.h>
#include <math.h>
#include <stdio.h>
#define SHOW(expr) printf("%s = %d\n", #expr, (int)(expr))
int main()
{
SHOW(FLT_EVAL_METHOD);
SHOW(sizeof(float));
SHOW(sizeof(float_t));
SHOW(sizeof(double));
SHOW(sizeof(double_t));
}
Possible output:
FLT_EVAL_METHOD = 1
sizeof(float) = 4
sizeof(float_t) = 8
sizeof(double) = 8
sizeof(double_t) = 8
References
- C23 standard (ISO/IEC 9899:2024):
- 7.12 Mathematics <math.h> (p: TBD)
- C17 standard (ISO/IEC 9899:2018):
- 7.12 Mathematics <math.h> (p: TBD)
- 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)