char and int Convert

int atoi(
   const char *str 
);
int _wtoi(
   const wchar_t *str 
);
int _atoi_l(
   const char *str,
   _locale_t locale
);
int _wtoi_l(
   const wchar_t *str,
   _locale_t locale
);

Parameters

str                                                     String to be converted. locale                                                Locale to use.

Return Value

Each function returns the int value produced by interpreting the input characters as a number. The return value is 0 for atoi and _wtoi, if the input cannot be converted to a value of that type.

In Visual C++ 2005, in the case of overflow with large negative integral values, LONG_MIN is returned. atoi and _wtoi return INT_MAX and INT_MIN on these conditions. In all out-of-range cases, errno is set to ERANGE. If the parameter passed in is NULL, the invalid parameter handler is invoked, as described in Parameter Validation. If execution is allowed to continue, these functions set errno to EINVAL and return 0.

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.

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.