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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
|
#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; }
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.