129 lines
3.3 KiB
C++
129 lines
3.3 KiB
C++
// Filename: pstrtod.cxx
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// Created by: drose (13Jun09)
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//
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////////////////////////////////////////////////////////////////////
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//
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// PANDA 3D SOFTWARE
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// Copyright (c) Carnegie Mellon University. All rights reserved.
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//
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// All use of this software is subject to the terms of the revised BSD
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// license. You should have received a copy of this license along
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// with this source code in a file named "LICENSE."
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//
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////////////////////////////////////////////////////////////////////
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#include "pstrtod.h"
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#include <ctype.h>
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#include <math.h>
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////////////////////////////////////////////////////////////////////
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// Function: pstrtod
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// Description: This function re-implements strtod, to avoid the
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// problems that occur when the LC_NUMERIC locale gets
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// set to anything other than "C". Regardless of the
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// user's locale, we need to be able to parse
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// floating-point numbers internally understanding a "."
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// as the decimal point.
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////////////////////////////////////////////////////////////////////
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double
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pstrtod(const char *nptr, char **endptr) {
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// First, skip whitespace.
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const char *p = nptr;
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while (isspace(*p)) {
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++p;
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}
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// Skip an optional leading sign.
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char sign = '+';
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if (*p == '+' || *p == '-') {
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sign = *p;
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++p;
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}
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double value = 0.0;
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if (isalpha(*p)) {
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// For special cases like "inf" and "nan", pass these up to the
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// system implementation of strtod.
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return strtod(nptr, endptr);
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}
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// Start reading decimal digits to the left of the decimal point.
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bool found_digits = false;
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while (isdigit(*p)) {
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value = (value * 10.0) + (*p - '0');
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found_digits = true;
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++p;
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}
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if (*p == '.') {
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++p;
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// Read decimal digits to the right of the decimal point.
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double multiplicand = 0.1;
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while (isdigit(*p)) {
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value += (*p - '0') * multiplicand;
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++p;
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found_digits = true;
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multiplicand *= 0.1;
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}
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}
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if (!found_digits) {
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// Not a valid float.
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if (endptr != NULL) {
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*endptr = (char *)nptr;
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}
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return 0.0;
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}
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if (tolower(*p) == 'e') {
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// There's an exponent.
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++p;
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char esign = '+';
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if (*p == '+' || *p == '-') {
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esign = *p;
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++p;
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}
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// Start reading decimal digits to the left of the decimal point.
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double evalue = 0.0;
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while (isdigit(*p)) {
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evalue = (evalue * 10.0) + (*p - '0');
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++p;
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}
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if (esign == '-') {
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value /= pow(evalue, 10.0);
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} else {
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value *= pow(evalue, 10.0);
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}
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}
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if (sign == '-') {
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value = -value;
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}
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if (endptr != NULL) {
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*endptr = (char *)p;
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}
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return value;
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}
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////////////////////////////////////////////////////////////////////
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// Function: patof
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// Description: This function re-implements atof, to avoid the
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// problems that occur when the LC_NUMERIC locale gets
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// set to anything other than "C". Regardless of the
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// user's locale, we need to be able to parse
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// floating-point numbers internally understanding a "."
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// as the decimal point.
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////////////////////////////////////////////////////////////////////
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double
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patof(const char *str) {
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return pstrtod(str, (char **)NULL);
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}
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