nan, nanf, nanl
Defined in header <math.h>
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(since C99) | |
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(since C99) | |
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(since C99) |
Converts the implementation-defined character string arg
into the corresponding quiet NaN value, as if by calling strtof
, strtod
, or strtold
, respectively, as follows:
The call nan("n-char-sequence")
, where n-char-sequence
is a sequence of digits, Latin letters, and underscores, is equivalent to the call strtod("NAN(n-char-sequence)", (char**)NULL);
.
The call nan("")
is equivalent to the call strtod("NAN()", (char**)NULL);
.
The call nan("string")
, where string
is neither an n-char-sequence nor an empty string, is equivalent to the call strtod("NAN", (char**)NULL);
.
Parameters
arg | - | narrow character string identifying the contents of a NaN |
Return value
The quiet NaN value that corresponds to the identifying string arg
or zero if the implementation does not support quiet NaNs.
Example
#include <stdio.h>
#include <math.h>
#include <stdint.h>
#include <inttypes.h>
#include <string.h>
int main(void)
{
double f1 = nan("1");
uint64_t f1n; memcpy(&f1n, &f1, sizeof f1);
printf("nan(\"1\") = %f (%" PRIx64 ")\n", f1, f1n);
double f2 = nan("2");
uint64_t f2n; memcpy(&f2n, &f2, sizeof f2);
printf("nan(\"2\") = %f (%" PRIx64 ")\n", f2, f2n);
double f3 = nan("0xF");
uint64_t f3n; memcpy(&f3n, &f3, sizeof f3);
printf("nan(\"0xF\") = %f (%" PRIx64 ")\n", f3, f3n);
}
Possible output:
nan("1") = nan (7ff8000000000001)
nan("2") = nan (7ff8000000000002)
nan("0xF") = nan (7ff800000000000f)
See also
(C99) |
checks if the given number is NaN (function) |
(C99) |
evaluates to a quiet NaN of type float (macro constant) |
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