2 dnl Copyright (C) 2002-2003, 2006-2010 Free Software Foundation, Inc.
3 dnl This file is free software; the Free Software Foundation
4 dnl gives unlimited permission to copy and/or distribute it,
5 dnl with or without modifications, as long as this notice is preserved.
7 AC_DEFUN([gl_FUNC_STRTOD],
9 AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
10 dnl Test whether strtod is declared.
11 dnl Don't call AC_FUNC_STRTOD, because it does not have the right guess
12 dnl when cross-compiling.
13 dnl Don't call AC_CHECK_FUNCS([strtod]) because it would collide with the
14 dnl ac_cv_func_strtod variable set by the AC_FUNC_STRTOD macro,
15 AC_CHECK_DECLS_ONCE([strtod])
16 if test $ac_cv_have_decl_strtod != yes; then
19 dnl Use undocumented macro to set POW_LIB correctly.
22 AC_CACHE_CHECK([whether strtod obeys C99], [gl_cv_func_strtod_works],
23 [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
27 /* Compare two numbers with ==.
28 This is a separate function because IRIX 6.5 "cc -O" miscompiles an
31 numeric_equal (double x, double y)
37 /* In some old versions of Linux (2000 or before), strtod mis-parses
38 strings with leading '+'. */
39 const char *string = " +69";
41 double value = strtod (string, &term);
42 if (value != 69 || term != (string + 4))
46 /* Under Solaris 2.4, strtod returns the wrong value for the
47 terminating character under some conditions. */
48 const char *string = "NaN";
50 strtod (string, &term);
51 if (term != string && *(term - 1) == 0)
55 /* Older glibc and Cygwin mis-parse "-0x". */
56 const char *string = "-0x";
58 double value = strtod (string, &term);
60 if (1.0 / value != -1.0 / zero || term != (string + 2))
64 /* Many platforms do not parse hex floats. */
65 const char *string = "0XaP+1";
67 double value = strtod (string, &term);
68 if (value != 20.0 || term != (string + 6))
72 /* Many platforms do not parse infinities. HP-UX 11.31 parses inf,
73 but mistakenly sets errno. */
74 const char *string = "inf";
78 value = strtod (string, &term);
79 if (value != HUGE_VAL || term != (string + 3) || errno)
83 /* glibc 2.7 and cygwin 1.5.24 misparse "nan()". */
84 const char *string = "nan()";
86 double value = strtod (string, &term);
87 if (numeric_equal (value, value) || term != (string + 5))
91 /* darwin 10.6.1 misparses "nan(". */
92 const char *string = "nan(";
94 double value = strtod (string, &term);
95 if (numeric_equal (value, value) || term != (string + 3))
99 [gl_cv_func_strtod_works=yes],
100 [gl_cv_func_strtod_works=no],
101 [gl_cv_func_strtod_works="guessing no"])])
102 if test "$gl_cv_func_strtod_works" != yes; then
105 dnl Use undocumented macro to set POW_LIB correctly.
111 # Prerequisites of lib/strtod.c.
112 # The need for pow() is already handled by AC_FUNC_STRTOD.
113 AC_DEFUN([gl_PREREQ_STRTOD], [:])