flt.c
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/*ident "@(#)cls4:lib/stream/flt.c 1.2.1.7" */
/*******************************************************************************
C++ source for the C++ Language System, Release 3.0. This product
is a new release of the original cfront developed in the computer
science research center of AT&T Bell Laboratories.
Copyright (c) 1993 UNIX System Laboratories, Inc.
Copyright (c) 1991, 1992 AT&T and UNIX System Laboratories, Inc.
Copyright (c) 1984, 1989, 1990 AT&T. All Rights Reserved.
THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE of AT&T and UNIX System
Laboratories, Inc. The copyright notice above does not evidence
any actual or intended publication of such source code.
*******************************************************************************/
#include <iostream.h>
#include <ctype.h>
#include <stdio.h>
#include <libc.h>
#include <string.h>
#include <math.h> // for frexp()
#define OSTREAM ostream
#define ISTREAM istream
// This file contains all the functions having to do with i/o of
// floats and doubles. It drags in lots of stuff from stdio, which
// is why I made it separate.
istream& ISTREAM::operator>>(double& d)
/*
{+|-} d* {.} d* { e|E {+|-} d+ }
except that
- a dot must be pre- or succeeded by at least one digit
- an exponent must be preceded by at least one digit
*/
{
register int c = 0;
register int anydigits = 0 ;
char buf[256];
register char* p = buf;
register streambuf* nbp = bp;
if (!ipfx() ) return *this ;
/* get the sign */
switch (c = nbp->sgetc()) {
case EOF:
setstate(eofbit|failbit) ;
return *this;
case '-':
case '+':
*p++ = c;
c = bp->snextc();
}
/* get integral part */
while (isdigit(c)) {
*p++ = c;
c = bp->snextc();
anydigits = 1 ;
}
/* get fraction */
if (c == '.') {
do {
*p++ = c;
c = bp->snextc();
anydigits = 1 ;
} while (isdigit(c));
}
/* get exponent */
if ( anydigits && (c == 'e' || c == 'E')) {
*p++ = c;
switch (c = nbp->snextc()) {
case EOF:
setstate(eofbit|failbit) ;
return *this;
case '-':
case '+':
*p++ = c;
c = bp->snextc();
}
while (isdigit(c)) {
*p++ = c;
c = bp->snextc();
}
}
*p = 0;
d = atof(buf);
if (c == EOF) setstate(eofbit) ;
if (!anydigits) setstate(badbit) ;
return *this;
}
istream& ISTREAM::operator>>(float& f)
{
double d;
if (!ipfx() ) return *this ;
*this >> d ;
if ( good() || rdstate() == eofbit ) f = d;
return *this;
}
ostream& OSTREAM::operator<<(float f) { return *this << (double)f ; }
//static const int fltbits = ios::scientific|ios::fixed|ios::uppercase ;
ostream& OSTREAM::operator<<(double d)
{
char buf[256];
int w = width(0) ;
int p = precision() ;
int explicitp = ( p > 0 ) || (flags()&ios::fixed) ;
if (!opfx()) return *this;
// long bits = flags() & fltbits ;
char fmt[256] ;
strcpy(fmt,"%") ;
if ( flags() & ios::showpoint ) {
strcat(fmt,"#") ;
}
if ( flags() & ios::showpos ) {
strcat(fmt,"+") ;
}
if ( explicitp ) {
strcat(fmt,".*") ;
}
long mode = flags()
& (ios::scientific|ios::fixed|ios::uppercase);
switch(mode) {
case ios::scientific : strcat(fmt,"e") ; break ;
case ios::scientific|ios::uppercase :
strcat(fmt,"E") ; break;
case ios::fixed : strcat(fmt,"f") ; break ;
case ios::fixed|ios::uppercase: strcat(fmt,"f") ; break ;
case ios::uppercase : strcat(fmt,"G") ; break ;
default : strcat(fmt,"g") ; break ;
}
char *result;
char *localbuf = 0;
result = buf;
if ( explicitp ) {
if (flags()&ios::fixed) {
int exponent;
/*double jnk =*/ frexp(d, &exponent);
localbuf = new char[p+(exponent>0 ? 4+exponent/3 : 4)];
// need 3 extra cells, one for sign,
// one for decimal point, one for null
sprintf(localbuf,fmt,p,d) ;
result = localbuf;
}
else if (p < 25) {
sprintf(buf,fmt,p,d) ;
}
else {
localbuf = new char[p + 10];
sprintf(localbuf,fmt,p,d) ;
result = localbuf;
}
}
else {
sprintf(buf,fmt,d) ;
}
int padf = w-strlen(result) ;
if ( padf < 0 ) padf = 0 ;
if ( padf && !(flags()&ios::left) ) {
if (flags()&ios::internal)
if (*result == '+' || *result == '-')
put(*result++);
while ( padf-- > 0 ) put(fill()) ;
}
*this << result ;
while ( padf-- > 0 ) put(fill()) ;
osfx() ;
if (localbuf != 0) delete localbuf;
return *this ;
}