gets函数怎样实现，百试不解，能给源代码？

[haomaer]

gets函数怎样实现，百试不解，能给源代码？

[EternalBlue]

下班走人咯，没时间写
反正可以一次读一个字节，判断是否为'\n'或EOF，不是就读下一个，是就返回

[EternalBlue]

忘了说，最好不要用gets。用fgets替代gets好点。
因为如果读出的字符串比你传入的参数长度还要长的话，indeterminate behavior may result。

[yxxng]

顶

[zhangfjj]

/***
*cgets.c - buffered keyboard input
*
* Copyright (c) 1989-1997, Microsoft Corporation. All rights reserved.
*
*Purpose:
* defines _cgets() - read a string directly from console
*
*******************************************************************************/

#include <cruntime.h>
#include <oscalls.h>
#include <mtdll.h>
#include <conio.h>
#include <stdlib.h>
#include <internal.h>

/*
* mask to clear the bits required to be 0 in the handle state passed to
* DOSSETFHSTATE.
*/
#define FHSTATEMASK 0xffd07888

/*
* declaration for console handle
*/

extern int _coninpfh;


/***
*char *_cgets(string) - read string from console
*
*Purpose:
* Reads a string from the console via ReadConsole on a cooked console
* handle. string[0] must contain the maximum length of the
* string. Returns pointer to str[2].
*
* NOTE: _cgets() does NOT check the pushback character buffer (i.e.,
* _chbuf). Thus, _cgets() will not return any character that is
* pushed back by the _ungetch() call.
*
*Entry:
* char *string - place to store read string, str[0] = max length.
*
*Exit:
* returns pointer to str[2], where the string starts.
* returns NULL if error occurs
*
*Exceptions:
*
*******************************************************************************/

char * __cdecl _cgets (
char *string
)
{
ULONG oldstate;
ULONG num_read;
char *result;

_mlock(_CONIO_LOCK); /* lock the console */

string[1] = 0; /* no chars read yet */
result = &string[2];

/*
* _coninpfh, the handle to the console input, is created the first
* time that either _getch() or _cgets() or _kbhit() is called.
*/

if ( _coninpfh == -2 )
__initconin();

if ( _coninpfh == -1 ) {
_munlock(_CONIO_LOCK); /* unlock the console */
return(NULL); /* return failure */
}

GetConsoleMode( (HANDLE)_coninpfh, &oldstate );
SetConsoleMode( (HANDLE)_coninpfh, ENABLE_LINE_INPUT | ENABLE_PROCESSED_INPUT |
ENABLE_ECHO_INPUT );

if ( !ReadConsole( (HANDLE)_coninpfh,
(LPVOID)result,
(unsigned char)string[0],
&num_read,
NULL )
)
result = NULL;

if ( result != NULL ) {

/* set length of string and null terminate it */

if (string[num_read] == '\r') {
string[1] = (char)(num_read - 2);
string[num_read] = '\0';
} else if ( (num_read == (ULONG)(unsigned char)string[0]) &&
(string[num_read + 1] == '\r') ) {
/* special case 1 - \r\n straddles the boundary */
string[1] = (char)(num_read -1);
string[1 + num_read] = '\0';
} else if ( (num_read == 1) && (string[2] == '\n') ) {
/* special case 2 - read a single '\n'*/
string[1] = string[2] = '\0';
} else {
string[1] = (char)num_read;
string[2 + num_read] = '\0';
}
}

SetConsoleMode( (HANDLE)_coninpfh, oldstate );

_munlock(_CONIO_LOCK); /* unlock the console */

return result;
}