autoconf/m4/c_printf_a.m4

   1 #
   2 # Determine if the printf() functions have the %a format character.
   3 # This is modified from:
   4 # http://www.gnu.org/software/ac-archive/htmldoc/ac_cxx_have_ext_slist.html
   5 AC_DEFUN([AC_C_PRINTF_A],
   6 [
   7         AC_MSG_CHECKING([for printf %a format specifier])
   8         AC_LANG_SAVE
   9         AC_LANG_C
  10         AC_RUN_IFELSE(
  11                 AC_LANG_PROGRAM([#include <stdio.h>
  12                                  #include <stdlib.h>],
  13                                  [[[
  14                                  volatile double A, B;
  15                                  char Buffer[100];
  16                                  A = 1;
  17                                  A /= 10.0;
  18                                  sprintf(Buffer, "%a", A);
  19                                  B = atof(Buffer);
  20                                  if (A != B)
  21                                                          return (1);
  22                                  if (A != 0x1.999999999999ap-4)
  23                                                          return (1);
  24                                  return (0);]]]),
  25                 ac_c_printf_a=yes,ac_c_printf_a=no)
  26         AC_LANG_RESTORE
  27         AC_MSG_RESULT($ac_c_printf_a)
  28         if test "$ac_c_printf_a" = "yes"; then
  29                 AC_DEFINE([HAVE_PRINTF_A],[1],[Define to have the %a format string])
  30         fi
  31 ])