fgets.c

C语言库函数的原型,有用的拿去

/***
*fgets.c - get string from a file
*
*       Copyright (c) Microsoft Corporation. All rights reserved.
*
*Purpose:
*       defines fgets() - read a string from a file
*
*******************************************************************************/

#include <cruntime.h>
#include <stdio.h>
#include <dbgint.h>
#include <file2.h>
#include <internal.h>
#include <mtdll.h>
#include <tchar.h>

/***
*char *fgets(string, count, stream) - input string from a stream
*
*Purpose:
*       get a string, up to count-1 chars or '\n', whichever comes first,
*       append '\0' and put the whole thing into string. the '\n' IS included
*       in the string. if count<=1 no input is requested. if EOF is found
*       immediately, return NULL. if EOF found after chars read, let EOF
*       finish the string as '\n' would.
*
*Entry:
*       char *string - pointer to place to store string
*       int count - max characters to place at string (include \0)
*       FILE *stream - stream to read from
*
*Exit:
*       returns string with text read from file in it.
*       if count <= 0 return NULL
*       if count == 1 put null string in string
*       returns NULL if error or end-of-file found immediately
*
*Exceptions:
*
*******************************************************************************/

_TSCHAR * __cdecl _fgetts (
        _TSCHAR *string,
        int count,
        FILE *str
        )
{
    REG1 FILE *stream;
    REG2 _TSCHAR *pointer = string;
    _TSCHAR *retval = string;
    int ch;

    _VALIDATE_RETURN(( string != NULL ) || ( count == 0 ), EINVAL, NULL);
    _VALIDATE_RETURN(( count >= 0 ), EINVAL, NULL);
    _VALIDATE_RETURN(( str != NULL ), EINVAL, NULL);

    if (count == 0)
    {
        return NULL;
    }

    /* The C Standard states the input buffer should remain
    unchanged if EOF is encountered immediately. Hence we
    do not blank out the input buffer here */

    /* Init stream pointer */
    stream = str;

    _lock_str(stream);
    __try {
#ifndef _UNICODE
        _VALIDATE_STREAM_ANSI_SETRET(stream, EINVAL, retval, NULL);
#endif  /* _UNICODE */
        if (retval!=NULL)
        {
            while (--count)
            {
                if ((ch = _fgettc_nolock(stream)) == _TEOF)
                {
                    if (pointer == string) {
                                    retval=NULL;
                                    goto done;
                    }

                    break;
                }

                if ((*pointer++ = (_TSCHAR)ch) == _T('\n'))
                    break;
            }

            *pointer = _T('\0');
        }


/* Common return */
done: ;
    }
    __finally {
        _unlock_str(stream);
    }

    return(retval);
}