Export (0) Print
Expand All
div
eof
Expand Minimize
This topic has not yet been rated - Rate this topic

_itoa_s, _i64toa_s, _ui64toa_s, _itow_s, _i64tow_s, _ui64tow_s

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
[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.

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.

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

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.

// 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)) );
    }
}
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)
Did you find this helpful?
(1500 characters remaining)
Thank you for your feedback
Show:
© 2014 Microsoft. All rights reserved.