ostrldbl.cpp

C标准库源代码

/***
* ostrldbl.cpp - definitions for ostream class operator<<(long double) functs
*
*       Copyright (c) 1991-1997, Microsoft Corporation.  All rights reserved.
*
*Purpose:
*       Contains the member function definitions for ostream
*       operator<<(long double).
*
*******************************************************************************/

#include <cruntime.h>
#include <internal.h>
#include <stdlib.h>
#include <stdio.h>
#include <float.h>
#include <iostream.h>
#pragma hdrstop

#pragma check_stack(on)         // large buffer(s)

ostream& ostream::operator<<(long double f)
{
_WINSTATIC char obuffer[28];
_WINSTATIC char fmt[12];
_WINSTATIC char leader[4];
    char * optr = obuffer;
    int x = 0;
    unsigned int curprecision = __min((unsigned)x_precision,LDBL_DIG);
    if (opfx()) {
        if (x_flags & ios::showpos)
            leader[x++] = '+';
        if (x_flags & ios::showpoint)
            leader[x++] = '#';  // show decimal and trailing zeros
        leader[x] = '\0';
        x = sprintf(fmt,"%%%s.%.0uLg",leader,curprecision) - 1;
        if ((x_flags & ios::floatfield)==ios::fixed)
            fmt[x] = 'f';
        else
            {
            if ((x_flags & ios::floatfield)==ios::scientific)
                fmt[x] = 'e';
            if (x_flags & uppercase)
                fmt[x] = (char)toupper(fmt[x]);
            }

        sprintf(optr,fmt,f);
        x = 0;
        if (*optr=='+' || *optr=='-')
            leader[x++] = *(optr++);
        leader[x] = '\0';
        writepad(leader,optr);
        osfx();
        }
    return *this;
}