mirror of https://github.com/python/cpython
60 lines
1.2 KiB
C
60 lines
1.2 KiB
C
/***********************************************************
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Copyright (c) 2000, BeOpen.com.
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Copyright (c) 1995-2000, Corporation for National Research Initiatives.
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Copyright (c) 1990-1995, Stichting Mathematisch Centrum.
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All rights reserved.
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See the file "Misc/COPYRIGHT" for information on usage and
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redistribution of this file, and for a DISCLAIMER OF ALL WARRANTIES.
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******************************************************************/
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/* Just in case you haven't got an atof() around...
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This one doesn't check for bad syntax or overflow,
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and is slow and inaccurate.
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But it's good enough for the occasional string literal... */
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#include "config.h"
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#include <ctype.h>
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double atof(char *s)
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{
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double a = 0.0;
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int e = 0;
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int c;
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while ((c = *s++) != '\0' && isdigit(c)) {
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a = a*10.0 + (c - '0');
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}
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if (c == '.') {
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while ((c = *s++) != '\0' && isdigit(c)) {
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a = a*10.0 + (c - '0');
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e = e-1;
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}
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}
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if (c == 'e' || c == 'E') {
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int sign = 1;
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int i = 0;
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c = *s++;
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if (c == '+')
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c = *s++;
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else if (c == '-') {
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c = *s++;
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sign = -1;
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}
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while (isdigit(c)) {
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i = i*10 + (c - '0');
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c = *s++;
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}
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e += i*sign;
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}
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while (e > 0) {
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a *= 10.0;
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e--;
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}
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while (e < 0) {
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a *= 0.1;
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e++;
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}
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return a;
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}
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