atoi使用時要注意了
這樣子寫有問題，可能導致down掉,因為ch沒有結(jié)束符.
但是我沒看出怎么當?shù)?br>
2007-10-09 下面這個程序不會當，但是 number 的值可能不是預期的。
int _tmain(int argc, _TCHAR* argv[])
{
char ch[1] = {0};
ch[0] = '9';
int number = ::atoi(ch);
std::cout << number << std::endl;
return 0;
}
以下是atox.c的源碼：
/***
*atox.c - atoi and atol conversion
*
* Copyright (c) Microsoft Corporation. All rights reserved.
*
*Purpose:
* Converts a character string into an int or long.
*
*******************************************************************************/
#include <cruntime.h>
#include <stdlib.h>
#include <ctype.h>
#include <mtdll.h>
#include <tchar.h>
#ifdef _MBCS
#undef _MBCS
#endif /* _MBCS */
#ifndef _UNICODE
#define _tchartodigit(c) ((c) >= '0' && (c) <= '9' ? (c) - '0' : -1)
#else /* _UNICODE */
int _wchartodigit(wchar_t);
#define _tchartodigit(c) _wchartodigit((wchar_t)(c))
#endif /* _UNICODE */
/***
*long atol(char *nptr) - Convert string to long
*
*Purpose:
* Converts ASCII string pointed to by nptr to binary.
* Overflow is not detected.
*
*Entry:
* nptr = ptr to string to convert
*
*Exit:
* return long int value of the string
*
*Exceptions:
* None - overflow is not detected.
*
*******************************************************************************/
long __cdecl _tstol(
const _TCHAR *nptr
)
{
int c; /* current char */
long total; /* current total */
int sign; /* if '-', then negative, otherwise positive */
#if defined (_MT) && !defined (_UNICODE)
pthreadlocinfo ptloci = _getptd()->ptlocinfo;
if ( ptloci != __ptlocinfo )
ptloci = __updatetlocinfo();
/* skip whitespace */
while ( __isspace_mt(ptloci, (int)(_TUCHAR)*nptr) )
#else /* defined (_MT) && !defined (_UNICODE) */
while ( _istspace((int)(_TUCHAR)*nptr) )
#endif /* defined (_MT) && !defined (_UNICODE) */
++nptr;
c = (int)(_TUCHAR)*nptr++;
sign = c; /* save sign indication */
if (c == _T('-') || c == _T('+'))
c = (int)(_TUCHAR)*nptr++; /* skip sign */
total = 0;
while ( (c = _tchartodigit(c)) != -1 ) {
total = 10 * total + c; /* accumulate digit */
c = (_TUCHAR)*nptr++; /* get next char */
}
if (sign == '-')
return -total;
else
return total; /* return result, negated if necessary */
}
/***
*int atoi(char *nptr) - Convert string to long
*
*Purpose:
* Converts ASCII string pointed to by nptr to binary.
* Overflow is not detected. Because of this, we can just use
* atol().
*
*Entry:
* nptr = ptr to string to convert
*
*Exit:
* return int value of the string
*
*Exceptions:
* None - overflow is not detected.
*
*******************************************************************************/
int __cdecl _tstoi(
const _TCHAR *nptr
)
{
return (int)_tstol(nptr);
}
#ifndef _NO_INT64
__int64 __cdecl _tstoi64(
const _TCHAR *nptr
)
{
int c; /* current char */
__int64 total; /* current total */
int sign; /* if '-', then negative, otherwise positive */
#if defined (_MT) && !defined (_UNICODE)
pthreadlocinfo ptloci = _getptd()->ptlocinfo;
if ( ptloci != __ptlocinfo )
ptloci = __updatetlocinfo();
/* skip whitespace */
while ( __isspace_mt(ptloci, (int)(_TUCHAR)*nptr) )
#else /* defined (_MT) && !defined (_UNICODE) */
while ( _istspace((int)(_TUCHAR)*nptr) )
#endif /* defined (_MT) && !defined (_UNICODE) */
++nptr;
c = (int)(_TUCHAR)*nptr++;
sign = c; /* save sign indication */
if (c == _T('-') || c == _T('+'))
c = (int)(_TUCHAR)*nptr++; /* skip sign */
total = 0;
while ( (c = _tchartodigit(c)) != -1 ) {
total = 10 * total + c; /* accumulate digit */
c = (_TUCHAR)*nptr++; /* get next char */
}
if (sign == _T('-'))
return -total;
else
return total; /* return result, negated if necessary */
}
#endif /* _NO_INT64 */
posted on 2007-09-28 09:19
七星重劍 閱讀(1702)
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