istrgint.cpp

C标准库源代码

/***
* istrgint.cpp - definitions for istream class core integer routines
*
*       Copyright (c) 1991-1997, Microsoft Corporation.  All rights reserved.
*
*Purpose:
*       Definitions of member function getint() for istream class.
*       [AT&T C++]
*
*******************************************************************************/

#include <cruntime.h>
#include <internal.h>
#include <ctype.h>
#include <iostream.h>
#pragma hdrstop

/***
*int istream::getint(char * buffer) - get an int
*
*Purpose:
*       Get an int from stream.
*
*Entry:
*       char * buffer   = area for number to be copied.
*
*Exit:
*       Returns base for conversion: (0, 2, 8, or 16).
*       If successful, buffer[] contains the number, followed by \0.
*
*Exceptions:
*       Sets ios::failbit on error forming number.
*       Sets ios::badbit on error after failbit
*       Sets ios::eofbit if at EOF at return
*
*******************************************************************************/
int     istream::getint(char * buffer)  // returns length
{
    int base, i;
    int c;
    int fDigit = 0;
    int bindex = 1;

    if (x_flags & ios::dec)
        base = 10;
    else if (x_flags & ios::hex)
        base = 16;
    else if (x_flags & ios::oct)
        base = 8;
    else
        base = 0;

    if (ipfx(0))
        {
        c=bp->sgetc();
        for (i = 0; i<MAXLONGSIZ-1; buffer[i] = (char)c,c=bp->snextc(),i++)
            {
            if (c==EOF)
                {
                state |= ios::eofbit;
                break;
                }
            if (!i)
                {
                if ((c=='-') || (c=='+'))
                    {
                    bindex++;
                    continue;
                    }
                }
            if ((i==bindex) && (buffer[i-1]=='0'))
                {
                if (((c=='x') || (c=='X')) && ((base==0) || (base==16)))
                    {
                    base = 16;  // simplifies matters
                    fDigit = 0;
                    continue;
                    }
                else if (base==0)
                    {
                    base = 8;
                    }
                }


            // now simply look for a digit and set fDigit if found else break

            if (base==16)
                {
                if (!isxdigit(c))
                    break;
                }
            else if ((!isdigit(c)) || ((base==8) && (c>'7')))
                break;

            fDigit++;
            }
        if (!fDigit)
            {
                state |= ios::failbit;
                while (i--)
                    {
                    if(bp->sputbackc(buffer[i])==EOF)
                        {
                        state |= ios::badbit;
                        break;
                        }
                    else
                        state &= ~(ios::eofbit);
                    }
                i=0;
                }
        // buffer contains a valid number or '\0'
        buffer[i] = '\0';
        isfx();
        }
    if (i==MAXLONGSIZ)
        {
        state |= ios::failbit;
        }
    return base;
}