safe-strtod.c: Split safe_strtod() into a library

Cherry pick from my phys305/zeta-and-step solutions.

diff --git a/safe-strtod.c b/safe-strtod.c
new file mode 100644 (file)
index 0000000..8396a0e
--- /dev/null
+++ b/safe-strtod.c
@@ -0,0 +1,41 @@
+/*
+Safe string-to-double conversion
+
+Copyright (C) 2013  W. Trevor King
+
+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 <http://www.gnu.org/licenses/>.
+*/
+
+#include <stdlib.h>       /* for strtod(), exit(), EXIT_* */
+#include <stdio.h>        /* for stderr, *printf(), perror() */
+#include <errno.h>        /* for errno */
+#include "safe-strtod.h"  /* check safe_strtod() declaration */
+
+double safe_strtod(const char *str, const char *name)
+{
+       char *endptr;
+       double x = strtod(str, &endptr);
+
+       if (errno) {
+               fprintf(stderr, "error converting %s to a double for %s:\n", str, name);
+               perror("strtod");
+               exit(EXIT_FAILURE);
+       }
+       if (endptr[0] != '\0') {
+               fprintf(stderr, "error converting %s to a double for %s:\n", str, name);
+               fprintf(stderr, "leftover characters: %s\n", endptr);
+               exit(EXIT_FAILURE);
+       }
+       return x;
+}

diff --git a/safe-strtod.h b/safe-strtod.h
new file mode 100644 (file)
index 0000000..e50a9c3
--- /dev/null
+++ b/safe-strtod.h
@@ -0,0 +1,25 @@
+/*
+Safe string-to-double conversion
+
+Copyright (C) 2013  W. Trevor King
+
+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 <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef _STRTOD_SAFE_H_
+#define _STRTOD_SAFE_H_
+
+double safe_strtod(const char *str, const char *name);
+
+#endif  /* _STRTOD_SAFE_H_ */