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#include <string.h>
extern char isspace(char c);
#ifdef __GNUC__
static inline char isdigit(char c) { return (c>='0' && c<='9'); }
#endif
double strtod(const char *nptr, char **endptr) {
double d=0;
register const char *c=nptr;
char neg=0;
while (*c && isspace(*c)) ++c;
switch (*c) {
case '-': neg=1;
case '+': c++; break;
default: break;
}
while (isdigit(*c)) {
d=d*10+(*c-'0');
++c;
}
if (*c=='.') {
double factor=.1;
while (isdigit(*++c)) {
d=d+(factor*(*c-'0'));
factor/=10;
}
}
if ((*c|32)=='e') {
int exp=0;
double factor=10;
if (c[1]<'0') {
switch (c[1]) {
case '-': factor=0.1;
case '+': c++; break;
default:
d=0;
c=nptr;
goto done;
}
}
while (isdigit(*++c))
exp=exp*10+(*c-'0');
while (exp) { /* XXX: this introduces rounding errors */
d*=factor; --exp;
}
}
done:
if (endptr) *endptr=(char*)c;
return d;
}
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