_itoa_s, _i64toa_s, _ui64toa_s, _itow_s, _i64tow_s, _ui64tow_s

最新推荐文章于 2022-06-19 14:35:36 发布

转载最新推荐文章于 2022-06-19 14:35:36 发布 · 618 阅读

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原文链接：http://www.cnblogs.com/cindy-hu-23/p/3548032.html

文章标签：

#ui #c/c++

本文介绍了一系列安全增强型函数，如 _itoa_s 和 _i64tow_s，用于将整数转换为字符串，并提供了示例代码。这些函数在 C 运行时库中实现了安全性改进。

Converts an integer to a string. These are versions of _itoa, _i64toa, _ui64toa, _itow, _i64tow, _ui64tow with security enhancements as described in Security Features in the CRT.

      
    
 
      errno_t _itoa_s(
   int value,
   char *buffer,
   size_t sizeInCharacters,
   int radix 
);
errno_t _i64toa_s(
   __int64 value,
   char *buffer,
   size_t sizeInCharacters,
   int radix 
);
errno_t _ui64toa_s(
   unsigned _int64 value,
   char *buffer,
   size_t sizeInCharacters,
   int radix 
);
errno_t _itow_s(
   int value,
   wchar_t *buffer,
   size_t sizeInCharacters,
   int radix 
);
errno_t _i64tow_s(
   __int64 value,
   wchar_t *buffer,
   size_t sizeInCharacters,
   int radix 
);
errno_t _ui64tow_s(
   unsigned __int64 value,
   wchar_t *buffer,
   size_t sizeInCharacters,
   int radix 
);
template <size_t size>
errno_t _itoa_s(
   int value,
   char (&buffer)[size],
   int radix 
); // C++ only
template <size_t size>
errno_t _itow_s(
   int value,
   wchar_t (&buffer)[size],
   int radix 
); // C++ only
 
     

Parameters

[in] value

Number to be converted.

[out] buffer

Filled with the result of the conversion.

[in] sizeInCharacters

Size of the buffer in single-byte characters or wide characters.

[in] radix

Base of value; which must be in the range 2–36.

Return Value

Zero if successful; an error code on failure. If any of the following conditions applies, the function invokes an invalid parameter handler, as described in Parameter Validation.

Error Conditions

value	buffer	sizeInCharacters	radix	Return
any	NULL	any	any	EINVAL
any	any	<=0	any	EINVAL
any	any	<= length of the result string required	any	EINVAL
any	any	any	radix < 2 or radix > 36	EINVAL

Security Issues

These functions can generate an access violation if buffer does not point to valid memory and is not NULL, or if the length of the buffer is not long enough to hold the result string.

Remarks

Except for the parameters and return value, the _itoa_s functions have the same behavior as the corresponding less secure versions.

In C++, using these functions is simplified by template overloads; the overloads can infer buffer length automatically (eliminating the need to specify a size argument) and they can automatically replace older, non-secure functions with their newer, secure counterparts. For more information, see Secure Template Overloads.

The debug versions of these functions first fill the buffer with 0xFD. To disable this behavior, use _CrtSetDebugFillThreshold.

Generic-Text Routine Mappings

Tchar.h routine	_UNICODE and _MBCS not defined	_MBCS defined	_UNICODE defined
_itot_s	_itoa_s	_itoa_s	_itow_s
_i64tot_s	_i64toa_s	_i64toa_s	_i64tow_s
_ui64tot_s	_ui64toa_s	_ui64toa_s	_ui64tow_s

Requirements

Routine	Required header
_itoa_s	<stdlib.h>
_i64toa_s	<stdlib.h>
_ui64toa_s	<stdlib.h>
_itow_s	<stdlib.h> or <wchar.h>
_i64tow_s	<stdlib.h> or <wchar.h>
_ui64tow_s	<stdlib.h> or <wchar.h>

For more compatibility information, see Compatibility in the Introduction.

Example

// crt_itoa_s.c
#include <stdlib.h>
#include <string.h>

int main( void )
{
    char buffer[65];
    int r;
    for( r=10; r>=2; --r )
    {
       _itoa_s( -1, buffer, 65, r );
       printf( "base %d: %s (%d chars)\n", r, buffer, strnlen(buffer, _countof(buffer)) );
    }
    printf( "\n" );
    for( r=10; r>=2; --r )
    {
       _i64toa_s( -1L, buffer, 65, r );
       printf( "base %d: %s (%d chars)\n", r, buffer, strnlen(buffer, _countof(buffer)) );
    }
    printf( "\n" );
    for( r=10; r>=2; --r )
    {
       _ui64toa_s( 0xffffffffffffffffL, buffer, 65, r );
       printf( "base %d: %s (%d chars)\n", r, buffer, strnlen(buffer, _countof(buffer)) );
    }
}

Output

base 10: -1 (2 chars)
base 9: 12068657453 (11 chars)
base 8: 37777777777 (11 chars)
base 7: 211301422353 (12 chars)
base 6: 1550104015503 (13 chars)
base 5: 32244002423140 (14 chars)
base 4: 3333333333333333 (16 chars)
base 3: 102002022201221111210 (21 chars)
base 2: 11111111111111111111111111111111 (32 chars)

base 10: -1 (2 chars)
base 9: 145808576354216723756 (21 chars)
base 8: 1777777777777777777777 (22 chars)
base 7: 45012021522523134134601 (23 chars)
base 6: 3520522010102100444244423 (25 chars)
base 5: 2214220303114400424121122430 (28 chars)
base 4: 33333333333333333333333333333333 (32 chars)
base 3: 11112220022122120101211020120210210211220 (41 chars)
base 2: 1111111111111111111111111111111111111111111111111111111111111111 (64 chars)

base 10: 18446744073709551615 (20 chars)
base 9: 145808576354216723756 (21 chars)
base 8: 1777777777777777777777 (22 chars)
base 7: 45012021522523134134601 (23 chars)
base 6: 3520522010102100444244423 (25 chars)
base 5: 2214220303114400424121122430 (28 chars)
base 4: 33333333333333333333333333333333 (32 chars)
base 3: 11112220022122120101211020120210210211220 (41 chars)
base 2: 1111111111111111111111111111111111111111111111111111111111111111 (64 chars)

.NET Framework Equivalent

System::Convert::ToString

转载于:https://www.cnblogs.com/cindy-hu-23/p/3548032.html