还是将源码贴出来看看吧....
/***
*scanf.c - read formatted data from stdin
*
*
Copyright (c) Microsoft Corporation. All rights reserved.
*
*Purpose:
*
defines scanf() - reads formatted data from stdin
*
*******************************************************************************/
#include <cruntime.h>
#include <stdio.h>
#include <dbgint.h>
#include <stdarg.h>
#include <file2.h>
#include <internal.h>
#include <mtdll.h>
/***
*int vscanf(format, ...) - read formatted data from stdin
*
*Purpose:
*
This is a helper function to be called from fscanf & fscanf_s
*
*Entry:
*
INPUTFN inputfn - scanf & scanf_s pass either _input_l or _input_s_l
*
which is then used to do the real work.
*
char *format - format string
*
va_list arglist - arglist of output pointers
*
*Exit:
*
returns number of fields read and assigned
*
*Exceptions:
*
*******************************************************************************/
int __cdecl vscanf (
INPUTFN inputfn,
const char *format,
_locale_t plocinfo,
va_list arglist
)
/*
* stdin 'SCAN', 'F'ormatted
*/
{
int retval;
_VALIDATE_RETURN( (format != NULL), EINVAL, EOF);
_lock_str2(0, stdin);
__try {
retval = (inputfn(stdin, format, plocinfo, arglist));
}
__finally {
_unlock_str2(0, stdin);
}
return(retval);
}
/***
*int scanf(format, ...) - read formatted data from stdin
*
*Purpose:
*
Reads formatted data from stdin into arguments.
_input_l does the real
*
work here.
*
*Entry:
*
char *format - format string
*
followed by list of pointers to storage for the data read.
The number
*
and type are controlled by the format string.
*
*Exit:
*
returns number of fields read and assigned
*
*Exceptions:
*
*******************************************************************************/
int __cdecl scanf (
const char *format,
...
)
{
va_list arglist;
va_start(arglist, format);
return vscanf(_input_l, format, NULL, arglist);
}
int __cdecl _scanf_l (
const char *format,
_locale_t plocinfo,
...
)
{
va_list arglist;
va_start(arglist, plocinfo);
return vscanf(_input_l, format, plocinfo, arglist);
}
/***
*int scanf_s(format, ...) - read formatted data from stdin
*
*
Same as scanf above except that it calls _input_s_l to do the real work.
*
_input_s_l has a size check for array parameters.
*
*******************************************************************************/
int __cdecl scanf_s (
const char *format,
...
)
{
va_list arglist;
va_start(arglist, format);
return vscanf(_input_s_l, format, NULL, arglist);
}
int __cdecl _scanf_s_l (
const char *format,
_locale_t plocinfo,
...
)
{
va_list arglist;
va_start(arglist, plocinfo);
return vscanf(_input_s_l, format, plocinfo, arglist);
}
其中有很多看不懂的宏定义以及类型定义，请各路大侠看看能不能解析一下，谢谢！
