2 dnl Copyright (C) 2002, 2003, 2006, 2007, 2008 Free Software
4 dnl This file is free software; the Free Software Foundation
5 dnl gives unlimited permission to copy and/or distribute it,
6 dnl with or without modifications, as long as this notice is preserved.
8 AC_DEFUN([gl_FUNC_STRTOD],
10 AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
12 dnl Note: AC_FUNC_STRTOD does AC_LIBOBJ(strtod).
13 if test $ac_cv_func_strtod = no; then
18 AC_CACHE_CHECK([whether strtod obeys C99], [gl_cv_func_strtod_works],
19 [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
22 /* Compare two numbers with ==.
23 This is a separate function because IRIX 6.5 "cc -O" miscompiles an
26 numeric_equal (double x, double y)
32 /* Older glibc and Cygwin mis-parse "-0x". */
33 const char *string = "-0x";
35 double value = strtod (string, &term);
37 if (1.0 / value != -1.0 / zero || term != (string + 2))
41 /* Many platforms do not parse hex floats. */
42 const char *string = "0XaP+1";
44 double value = strtod (string, &term);
45 if (value != 20.0 || term != (string + 6))
49 /* Many platforms do not parse infinities. */
50 const char *string = "inf";
52 double value = strtod (string, &term);
53 if (value != HUGE_VAL || term != (string + 3))
57 /* glibc 2.7 and cygwin 1.5.24 misparse "nan()". */
58 const char *string = "nan()";
60 double value = strtod (string, &term);
61 if (numeric_equal (value, value) || term != (string + 5))
65 [gl_cv_func_strtod_works=yes],
66 [gl_cv_func_strtod_works=no],
67 [gl_cv_func_strtod_works="guessing no"])])
68 if test "$gl_cv_func_strtod_works" != yes; then
71 dnl Use undocumented macro to set POW_LIB correctly.
77 # Prerequisites of lib/strtod.c.
78 # The need for pow() is already handled by AC_FUNC_STRTOD.
79 AC_DEFUN([gl_PREREQ_STRTOD], [:])