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quadmath_snprintf — Convert to stringThe function quadmath_snprintf converts a __float128 floating-point
number into a string. It is a specialized alternative to snprintf, where
the format string is restricted to a single conversion specifier with Q
modifier and conversion specifier e, E, f, F, g,
G, a or A, with no extra characters before or after the
conversion specifier. The %m$ or *m$ style must not be used in
the format.
int quadmath_snprintf (char *s, size_t size, const char *format, ...)
| s | output string |
| size | byte size of the string, including tailing NUL |
| format | conversion specifier string |
On some targets when supported by the C library hooks are installed
for printf family of functions, so that printf ("%Qe", 1.2Q);
etc. works too.
#include <quadmath.h>
#include <stdlib.h>
#include <stdio.h>
int main ()
{
__float128 r;
int prec = 20;
int width = 46;
char buf[128];
r = 2.0q;
r = sqrtq (r);
int n = quadmath_snprintf (buf, sizeof buf, "%+-#*.20Qe", width, r);
if ((size_t) n < sizeof buf)
printf ("%s\n", buf);
/* Prints: +1.41421356237309504880e+00 */
quadmath_snprintf (buf, sizeof buf, "%Qa", r);
if ((size_t) n < sizeof buf)
printf ("%s\n", buf);
/* Prints: 0x1.6a09e667f3bcc908b2fb1366ea96p+0 */
n = quadmath_snprintf (NULL, 0, "%+-#46.*Qe", prec, r);
if (n > -1)
{
char *str = malloc (n + 1);
if (str)
{
quadmath_snprintf (str, n + 1, "%+-#46.*Qe", prec, r);
printf ("%s\n", str);
/* Prints: +1.41421356237309504880e+00 */
}
free (str);
}
return 0;
}