Re: Easy Accurate Reading and Writing of Floating-Point Numbers

["Marc Nieper-Wißkirchen" <marc.nieper+gnu@gmail.com>]

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Please see the attached patch file, my first attempt (and first
contribution to Gnulib).

Am Di., 19. Mai 2020 um 17:51 Uhr schrieb Paul Eggert <eggert@cs.ucla.edu>:
>
> On 5/19/20 8:35 AM, Marc Nieper-Wißkirchen wrote:
> >> It is, however, locale-dependent, and there is no "c_dtoastr"
> >> version as there is a "c_strtod". (Could we get such a wrapper?)
> > Or a version "c_dtoastr" that uses "c_snprintf" and "c_strtod" internally.
>
> Yes, that'd be good to have. Could you write that?

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From f4308c51cc73a8b1397c436f8dd667e15d6d0b9b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marc=20Nieper-Wi=C3=9Fkirchen?= <marc@nieper-wisskirchen.de>
Date: Wed, 20 May 2020 13:59:31 +0200
Subject: [PATCH] New module to accurately print (long) doubles in C locale.

---
 ChangeLog                | 18 +++++++++++++
 MODULES.html.sh          |  2 ++
 lib/c-dtoastr.c          |  3 +++
 lib/c-ldtoastr.c         |  3 +++
 lib/ftoastr.c            | 23 +++++++++++-----
 lib/ftoastr.h            |  6 +++++
 modules/c-dtoastr        | 27 +++++++++++++++++++
 modules/c-dtoastr-tests  | 18 +++++++++++++
 modules/c-ldtoastr       | 27 +++++++++++++++++++
 modules/c-ldtoastr-tests | 18 +++++++++++++
 tests/test-c-dtoastr.c   | 58 ++++++++++++++++++++++++++++++++++++++++
 tests/test-c-dtoastr.sh  | 15 +++++++++++
 tests/test-c-ldtoastr.c  | 58 ++++++++++++++++++++++++++++++++++++++++
 tests/test-c-ldtoastr.sh | 15 +++++++++++
 14 files changed, 285 insertions(+), 6 deletions(-)
 create mode 100644 lib/c-dtoastr.c
 create mode 100644 lib/c-ldtoastr.c
 create mode 100644 modules/c-dtoastr
 create mode 100644 modules/c-dtoastr-tests
 create mode 100644 modules/c-ldtoastr
 create mode 100644 modules/c-ldtoastr-tests
 create mode 100644 tests/test-c-dtoastr.c
 create mode 100644 tests/test-c-dtoastr.sh
 create mode 100644 tests/test-c-ldtoastr.c
 create mode 100644 tests/test-c-ldtoastr.sh

diff --git a/ChangeLog b/ChangeLog
index 1c39b92e6..becb40eec 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,21 @@
+2020-05-20  Marc Nieper-Wißkirchen  <marc@nieper-wisskirchen.de>
+
+	c-dtoastr: new module
+	c-ldtoastr: new module
+	These modules provide the same functionality as the modules
+	dtoastr and ldtoastr except for the formatting taking place in the
+	C locale.
+	* MODULES.html.sh: Add c-dtoastr and c-ldtoastr.
+	* lib/c-dtoastr.c, lib/c-ldtoastr.c: New files
+	* lib/ftoastr.c: Prefix exported functions when the macro C_LOCALE is
+	defined.  Use c_snprintf and c_strtod/c_strtold instead of
+	snprintf and strtod/strtold whhen the macro C_LOCALE is defined.
+	* lib/ftoastr.h: Add prototypes for c_dtoastr and c_ldtoastr.
+	* modules/c-dtoastr, modules/c-dtoastr-tests, modules/c-ldtoastr,
+	modules/c-ldtoastr-tests: New files.
+	* tests/test-c-dtoastr.c, tests/test-c-dtoastr.sh,
+	tests-c-ldtoastr.c tests-c-ldtoastr.sh: New files.
+
 2020-05-19  Paul Eggert  <eggert@cs.ucla.edu>
 
 	ftoastr: fix ifndef typo
diff --git a/MODULES.html.sh b/MODULES.html.sh
index 318a15a1d..280bd14da 100755
--- a/MODULES.html.sh
+++ b/MODULES.html.sh
@@ -2319,6 +2319,8 @@ func_all_modules ()
   func_echo "$element"
 
   func_begin_table
+  func_module c-dtoastr
+  func_module c-ldtoast
   func_module dtoastr
   func_module ftoastr
   func_module intprops
diff --git a/lib/c-dtoastr.c b/lib/c-dtoastr.c
new file mode 100644
index 000000000..b57524fb1
--- /dev/null
+++ b/lib/c-dtoastr.c
@@ -0,0 +1,3 @@
+#define LENGTH 2
+#define C_LOCALE 1
+#include "ftoastr.c"
diff --git a/lib/c-ldtoastr.c b/lib/c-ldtoastr.c
new file mode 100644
index 000000000..5446fc3e7
--- /dev/null
+++ b/lib/c-ldtoastr.c
@@ -0,0 +1,3 @@
+#define LENGTH 3
+#define C_LOCALE 1
+#include "ftoastr.c"
diff --git a/lib/ftoastr.c b/lib/ftoastr.c
index 7a7d4113c..47a83152e 100644
--- a/lib/ftoastr.c
+++ b/lib/ftoastr.c
@@ -33,20 +33,28 @@
 #include <stdio.h>
 #include <stdlib.h>
 
+#ifdef C_LOCALE
+# include "c-snprintf.h"
+# include "c-strtod.h"
+# define PREFIX(name) c_ ## name
+#else
+# define PREFIX(name) name
+#endif
+
 #if LENGTH == 3
 # define FLOAT long double
 # define FLOAT_DIG LDBL_DIG
 # define FLOAT_MIN LDBL_MIN
 # define FLOAT_PREC_BOUND _GL_LDBL_PREC_BOUND
-# define FTOASTR ldtoastr
+# define FTOASTR PREFIX (ldtoastr)
 # define PROMOTED_FLOAT long double
-# define STRTOF strtold
+# define STRTOF PREFIX (strtold)
 #elif LENGTH == 2
 # define FLOAT double
 # define FLOAT_DIG DBL_DIG
 # define FLOAT_MIN DBL_MIN
 # define FLOAT_PREC_BOUND _GL_DBL_PREC_BOUND
-# define FTOASTR dtoastr
+# define FTOASTR PREFIX (dtoastr)
 # define PROMOTED_FLOAT double
 #else
 # define LENGTH 1
@@ -54,7 +62,7 @@
 # define FLOAT_DIG FLT_DIG
 # define FLOAT_MIN FLT_MIN
 # define FLOAT_PREC_BOUND _GL_FLT_PREC_BOUND
-# define FTOASTR ftoastr
+# define FTOASTR PREFIX (ftoastr)
 # define PROMOTED_FLOAT double
 # if HAVE_STRTOF
 #  define STRTOF strtof
@@ -65,13 +73,16 @@
    may generate one or two extra digits, but that's better than not
    working at all.  */
 #ifndef STRTOF
-# define STRTOF strtod
+# define STRTOF PREFIX (strtod)
 #endif
 
 /* On hosts where it's not known that snprintf works, use sprintf to
    implement the subset needed here.  Typically BUFSIZE is big enough
    and there's little or no performance hit.  */
-#if ! GNULIB_SNPRINTF
+#ifdef C_LOCALE
+# undef snprintf
+# define snprintf c_snprintf
+#elif ! GNULIB_SNPRINTF
 # undef snprintf
 # define snprintf ftoastr_snprintf
 static int
diff --git a/lib/ftoastr.h b/lib/ftoastr.h
index 852e4000d..78b569f3d 100644
--- a/lib/ftoastr.h
+++ b/lib/ftoastr.h
@@ -49,6 +49,12 @@ int  ftoastr (char *buf, size_t bufsize, int flags, int width,       float x);
 int  dtoastr (char *buf, size_t bufsize, int flags, int width,      double x);
 int ldtoastr (char *buf, size_t bufsize, int flags, int width, long double x);
 
+/* The last two functions except that the formatting takes place in
+   the C locale.  */
+int  c_dtoastr (char *buf, size_t bufsize, int flags, int width,      double x);
+int c_ldtoastr (char *buf, size_t bufsize, int flags, int width, long double x);
+
+
 /* Flag values for ftoastr etc.  These can be ORed together.  */
 enum
   {
diff --git a/modules/c-dtoastr b/modules/c-dtoastr
new file mode 100644
index 000000000..fd0054ade
--- /dev/null
+++ b/modules/c-dtoastr
@@ -0,0 +1,27 @@
+Description:
+Convert double to accurate string in C locale.
+
+Files:
+lib/ftoastr.h
+lib/ftoastr.c
+lib/c-dtoastr.c
+
+Depends-on:
+extensions
+intprops
+c-snprintf
+c-strtod
+
+configure.ac:
+
+Makefile.am:
+lib_SOURCES += c-dtoastr.c
+
+Include:
+"ftoastr.h"
+
+License:
+GPL
+
+Maintainer:
+Marc Nieper-Wisskirchen
\ No newline at end of file
diff --git a/modules/c-dtoastr-tests b/modules/c-dtoastr-tests
new file mode 100644
index 000000000..687d7669b
--- /dev/null
+++ b/modules/c-dtoastr-tests
@@ -0,0 +1,18 @@
+Files:
+tests/test-c-dtoastr.c
+tests/test-c-dtoastr.sh
+m4/locale-fr.m4
+tests/macros.h
+
+Depends-on:
+setlocale
+snprintf
+
+configure.ac:
+gt_LOCALE_FR
+
+Makefile.am:
+TESTS += test-c-dtoastr.sh
+TESTS_ENVIRONMENT += LOCALE_FR='@LOCALE_FR@'
+check_PROGRAMS += test-c-dtoastr
+test_c_dtoastr_LDADD = $(LDADD) $(LIB_SETLOCALE)
diff --git a/modules/c-ldtoastr b/modules/c-ldtoastr
new file mode 100644
index 000000000..ce1e9dbf7
--- /dev/null
+++ b/modules/c-ldtoastr
@@ -0,0 +1,27 @@
+Description:
+Convert long double to accurate string in C locale.
+
+Files:
+lib/ftoastr.h
+lib/ftoastr.c
+lib/c-ldtoastr.c
+
+Depends-on:
+extensions
+intprops
+c-snprintf
+c-strtold
+
+configure.ac:
+
+Makefile.am:
+lib_SOURCES += c-ldtoastr.c
+
+Include:
+"ftoastr.h"
+
+License:
+GPL
+
+Maintainer:
+Marc Nieper-Wisskirchen
\ No newline at end of file
diff --git a/modules/c-ldtoastr-tests b/modules/c-ldtoastr-tests
new file mode 100644
index 000000000..2d4c7f81e
--- /dev/null
+++ b/modules/c-ldtoastr-tests
@@ -0,0 +1,18 @@
+Files:
+tests/test-c-ldtoastr.c
+tests/test-c-ldtoastr.sh
+m4/locale-fr.m4
+tests/macros.h
+
+Depends-on:
+setlocale
+snprintf
+
+configure.ac:
+gt_LOCALE_FR
+
+Makefile.am:
+TESTS += test-c-ldtoastr.sh
+TESTS_ENVIRONMENT += LOCALE_FR='@LOCALE_FR@'
+check_PROGRAMS += test-c-ldtoastr
+test_c_ldtoastr_LDADD = $(LDADD) $(LIB_SETLOCALE)
diff --git a/tests/test-c-dtoastr.c b/tests/test-c-dtoastr.c
new file mode 100644
index 000000000..373e7c4bc
--- /dev/null
+++ b/tests/test-c-dtoastr.c
@@ -0,0 +1,58 @@
+/* Test of c_dtoastr() function.
+   Copyright (C) 2020 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+#include "ftoastr.h"
+
+#include <locale.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "macros.h"
+
+int
+main (int argc, char *argv[])
+{
+  /* configure should already have checked that the locale is supported.  */
+  if (setlocale (LC_ALL, "") == NULL)
+    return 1;
+
+  /* Test behaviour of snprintf() as a "control group".
+     (We should be running in a locale where ',' is the decimal point.) */
+  {
+    char s[16];
+
+    snprintf (s, sizeof s, "%#.0f", 1.0);
+    if (!strcmp (s, "1."))
+      {
+        /* Skip the test, since we're not in a useful locale for testing. */
+        return 77;
+      }
+    ASSERT (!strcmp (s, "1,"));
+  }
+
+  /* Test behaviour of c_dtoastr().
+     It should always use '.' as the decimal point. */
+  {
+    char buf[DBL_BUFSIZE_BOUND];
+
+    c_dtoastr (buf, sizeof buf, 0, 0, 0.1);
+    ASSERT (!strcmp (buf, "0.1"));
+  }
+
+  return 0;
+}
diff --git a/tests/test-c-dtoastr.sh b/tests/test-c-dtoastr.sh
new file mode 100644
index 000000000..ef0e459b4
--- /dev/null
+++ b/tests/test-c-dtoastr.sh
@@ -0,0 +1,15 @@
+#!/bin/sh
+
+# Test in an ISO-8859-1 or ISO-8859-15 locale.
+: ${LOCALE_FR=fr_FR}
+if test $LOCALE_FR = none; then
+  if test -f /usr/bin/localedef; then
+    echo "Skipping test: no traditional french locale is installed"
+  else
+    echo "Skipping test: no traditional french locale is supported"
+  fi
+  exit 77
+fi
+
+LC_ALL=$LOCALE_FR \
+${CHECKER} ./test-c-dtoastr${EXEEXT} 1
diff --git a/tests/test-c-ldtoastr.c b/tests/test-c-ldtoastr.c
new file mode 100644
index 000000000..140f0c6d8
--- /dev/null
+++ b/tests/test-c-ldtoastr.c
@@ -0,0 +1,58 @@
+/* Test of c_ldtoastr() function.
+   Copyright (C) 2020 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+#include "ftoastr.h"
+
+#include <locale.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "macros.h"
+
+int
+main (int argc, char *argv[])
+{
+  /* configure should already have checked that the locale is supported.  */
+  if (setlocale (LC_ALL, "") == NULL)
+    return 1;
+
+  /* Test behaviour of snprintf() as a "control group".
+     (We should be running in a locale where ',' is the decimal point.) */
+  {
+    char s[16];
+
+    snprintf (s, sizeof s, "%#.0f", 1.0);
+    if (!strcmp (s, "1."))
+      {
+        /* Skip the test, since we're not in a useful locale for testing. */
+        return 77;
+      }
+    ASSERT (!strcmp (s, "1,"));
+  }
+
+  /* Test behaviour of c_ldtoastr().
+     It should always use '.' as the decimal point. */
+  {
+    char buf[DBL_BUFSIZE_BOUND];
+
+    c_ldtoastr (buf, sizeof buf, 0, 0, 0.1);
+    ASSERT (!strcmp (buf, "0.1"));
+  }
+
+  return 0;
+}
diff --git a/tests/test-c-ldtoastr.sh b/tests/test-c-ldtoastr.sh
new file mode 100644
index 000000000..ad7a32a14
--- /dev/null
+++ b/tests/test-c-ldtoastr.sh
@@ -0,0 +1,15 @@
+#!/bin/sh
+
+# Test in an ISO-8859-1 or ISO-8859-15 locale.
+: ${LOCALE_FR=fr_FR}
+if test $LOCALE_FR = none; then
+  if test -f /usr/bin/localedef; then
+    echo "Skipping test: no traditional french locale is installed"
+  else
+    echo "Skipping test: no traditional french locale is supported"
+  fi
+  exit 77
+fi
+
+LC_ALL=$LOCALE_FR \
+${CHECKER} ./test-c-ldtoastr${EXEEXT} 1
-- 
2.20.1