| _access, _waccess | _access_s, _waccess_s | Determine file-access permission |
| _alloca | _malloca | Allocate memory on the stack |
| asctime, _wasctime | asctime_s, _wasctime_s | Convert time from type struct tm to character string |
| bsearch | bsearch_s | Perform a binary search of a sorted array |
| Obsolete function | _cgets_s, _cgetws_s | Get a character string from the console |
| _chsize | _chsize_s | Change the size of a file |
| clearerr | clearerr_s | Reset the error indicator for a stream |
| _control87, _controlfp, __control87_2 | _controlfp_s | Get and set the floating-point control word |
| _cprintf, _cprintf_l, _cwprintf, _cwprintf_l | _cprintf_s, _cprintf_s_l, _cwprintf_s, _cwprintf_s_l | Format and print to the console |
| _cscanf, _cscanf_l, _cwscanf, _cwscanf_l | _cscanf_s, _cscanf_s_l, _cwscanf_s, _cwscanf_s_l | Read formatted data from the console |
| ctime, _ctime32, _ctime64, _wctime, _wctime32, _wctime64 | _ctime_s, _ctime32_s, _ctime64_s, _wctime_s, _wctime32_s, _wctime64_s | Convert time from type time_t, __time32_t or __time64_t to character string |
| _ecvt | _ecvt_s | Convert a double number to a string |
| _fcvt | _fcvt_s | Converts a floating-point number to a string |
| fopen, _wfopen | fopen_s, _wfopen_s | Open a file |
| fprintf, _fprintf_l, fwprintf, _fwprintf_l | fprintf_s, _fprintf_s_l, fwprintf_s, _fwprintf_s_l | Print formatted data to a stream |
| fread | fread_s | Read from a file |
| _fread_nolock | _fread_nolock_s | Read from a file without using a multi-thread write lock |
| freopen, _wfreopen | freopen_s, _wfreopen_s | Reopen the file |
| fscanf, _fscanf_l, fwscanf, _fwscanf_l | fscanf_s, _fscanf_s_l, fwscanf_s, _fwscanf_s_l | Read formatted data from a stream |
| _ftime, _ftime32, _ftime64 | _ftime_s, _ftime32_s, _ftime64_s | Get the current time |
| _gcvt | _gcvt_s | Convert a floating-point value to a string, and store it in a buffer |
| getenv, _wgetenv | getenv_s, _wgetenv_s | Get a value from the current environment. |
| Obsolete function | gets_s, _getws_s | Get a line from the stdin stream |
| gmtime, _gmtime32, _gmtime64 | _gmtime32_s, _gmtime64_s | Convert time from type time_t to struct``tm or from type __time64_t to struct tm |
| _itoa, _i64toa, _ui64toa, _itow, _i64tow, _ui64tow | _itoa_s, _i64toa_s, _ui64toa_s, _itow_s, _i64tow_s, _ui64tow_s | Convert an integer to a string |
| _lfind | _lfind_s | Perform a linear search for the specified key |
| localtime, _localtime32, _localtime64 | localtime_s, _localtime32_s, _localtime64_s | Convert time from type time_t to struct tm or from type __time64_t to struct tmwith local correction |
| _lsearch | _lsearch_s | Perform a linear search for a value; adds to end of list if not found |
| _ltoa, _ltow | _ltoa_s, _ltow_s | Convert a long integer to a string |
| _makepath, _wmakepath | _makepath_s, _wmakepath_s | Create a path name from components |
| _mbccpy, _mbccpy_l | _mbccpy_s, _mbccpy_s_l | Copy a multibyte character from one string to another string |
| _mbsnbcat, _mbsnbcat_l | _mbsnbcat_s, _mbsnbcat_s_l | Append, at most, the first n bytes of one multibyte character string to another |
| _mbsnbcpy, _mbsnbcpy_l | _mbsnbcpy_s, _mbsnbcpy_s_l | Copy n bytes of a string to a destination string |
| _mbsnbset, _mbsnbset_l | _mbsnbset_s, _mbsnbset_s_l | Set the first n bytes of a string to a specified character |
| mbsrtowcs | mbsrtowcs_s | Convert a multibyte character string to a corresponding wide character string |
| mbstowcs, _mbstowcs_l | mbstowcs_s, _mbstowcs_s_l | Convert a sequence of multibyte characters to a corresponding sequence of wide characters |
| memcpy, wmemcpy | memcpy_s, wmemcpy_s | Copy characters between buffers |
| memmove, wmemmove | memmove_s, wmemmove_s | Move one buffer to another |
| _mktemp, _wmktemp | _mktemp_s, _wmktemp_s | Create a unique filename |
| printf, _printf_l, wprintf, _wprintf_l | printf_s, _printf_s_l, wprintf_s, _wprintf_s_l | Print formatted output to the standard output stream |
| _putenv, _wputenv | _putenv_s, _wputenv_s | Create, modify, or remove environment variables |
| qsort | qsort_s | Perform a quick sort |
| rand | rand_s | Generate a pseudorandom number |
| scanf, _scanf_l, wscanf, _wscanf_l | scanf_s, _scanf_s_l, wscanf_s, _wscanf_s_l | Read formatted data from the standard input stream |
| _searchenv, _wsearchenv | _searchenv_s, _wsearchenv_s | Search for a file using environment paths |
| snprintf, _snprintf, _snprintf_l, _snwprintf, _snwprintf_l | _snprintf_s, _snprintf_s_l, _snwprintf_s, _snwprintf_s_l | Write formatted data to a string |
| _snscanf, _snscanf_l, _snwscanf, _snwscanf_l | _snscanf_s, _snscanf_s_l, _snwscanf_s, _snwscanf_s_l | Read formatted data of a specified length from a string. |
| _sopen, _wsopen | _sopen_s, _wsopen_s | Open a file for sharing |
| _splitpath, _wsplitpath | _splitpath_s, _wsplitpath_s | Break a path name into components |
| sprintf, _sprintf_l, swprintf, _swprintf_l, __swprintf_l | sprintf_s, _sprintf_s_l, swprintf_s, _swprintf_s_l | Write formatted data to a string |
| sscanf, _sscanf_l, swscanf, _swscanf_l | sscanf_s, _sscanf_s_l, swscanf_s, _swscanf_s_l | Read formatted data from a string |
| strcat, wcscat, _mbscat | strcat_s, wcscat_s, _mbscat_s | Append a string |
| strcpy, wcscpy, _mbscpy | strcpy_s, wcscpy_s, _mbscpy_s | Copy a string |
| _strdate, _wstrdate | _strdate_s, _wstrdate_s | Return current system date as string |
| strerror, _strerror, _wcserror, __wcserror | strerror_s, _strerror_s, _wcserror_s, __wcserror_s | Get a system error message (strerror, _wcserror) or print a user-supplied error message (_strerror, __wcserror) |
| _strlwr, _wcslwr, _mbslwr, _strlwr_l, _wcslwr_l, _mbslwr_l | _strlwr_s, _strlwr_s_l, _mbslwr_s, _mbslwr_s_l, _wcslwr_s, _wcslwr_s_l | Convert a string to lowercase |
| strncat, _strncat_l, wcsncat, _wcsncat_l, _mbsncat, _mbsncat_l | strncat_s, _strncat_s_l, wcsncat_s, _wcsncat_s_l, _mbsncat_s, _mbsncat_s_l | Append characters to a string |
| strncpy, _strncpy_l, wcsncpy, _wcsncpy_l, _mbsncpy, _mbsncpy_l | strncpy_s, _strncpy_s_l, wcsncpy_s, _wcsncpy_s_l, _mbsncpy_s, _mbsncpy_s_l | Copy characters of one string to another |
| _strnset, _strnset_l, _wcsnset, _wcsnset_l, _mbsnset, _mbsnset_l | _strnset_s, _strnset_s_l, _wcsnset_s, _wcsnset_s_l, _mbsnset_s, _mbsnset_s_l | Set the first n characters of a string to the specified character |
| _strset, _strset_l, _wcsset, _wcsset_l, _mbsset, _mbsset_l | _strset_s, _strset_s_l, _wcsset_s, _wcsset_s_l, _mbsset_s, _mbsset_s_l | Set all the characters of a string to the specified character |
| _strtime, _wstrtime | _strtime_s, _wstrtime_s | Return current system time as string |
| strtok, _strtok_l, wcstok, _wcstok_l, _mbstok, _mbstok_l | strtok_s, _strtok_s_l, wcstok_s, _wcstok_s_l, _mbstok_s, _mbstok_s_l | Find the next token in a string, using the current locale or a locale passed in |
| _strupr, _strupr_l, _mbsupr, _mbsupr_l, _wcsupr_l, _wcsupr | _strupr_s, _strupr_s_l, _mbsupr_s, _mbsupr_s_l, _wcsupr_s, _wcsupr_s_l | Convert a string to uppercase |
| tmpfile | tmpfile_s | Create a temporary file |
| _tempnam, _wtempnam, tmpnam, _wtmpnam | tmpnam_s, _wtmpnam_s | Generate names you can use to create temporary files |
| _ultoa, _ultow | _ultoa_s, _ultow_s | Convert an unsigned long integer to a string |
| _umask | _umask_s | Set the default file-permission mask |
| _vcprintf, _vcprintf_l, _vcwprintf, _vcwprintf_l | _vcprintf_s, _vcprintf_s_l, _vcwprintf_s, _vcwprintf_s_l | Write formatted output to the console using a pointer to a list of arguments |
| vfprintf, _vfprintf_l, vfwprintf, _vfwprintf_l | vfprintf_s, _vfprintf_s_l, vfwprintf_s, _vfwprintf_s_l | Write formatted output using a pointer to a list of arguments |
| vfscanf, vfwscanf | vfscanf_s, vfwscanf_s | Read formatted data from a stream |
| vprintf, _vprintf_l, vwprintf, _vwprintf_l | vprintf_s, _vprintf_s_l, vwprintf_s, _vwprintf_s_l | Write formatted output using a pointer to a list of arguments |
| vscanf, vwscanf | vscanf_s, vwscanf_s | Read formatted data from the standard input stream |
| vsnprintf, _vsnprintf, _vsnprintf_l, _vsnwprintf, _vsnwprintf_l | vsnprintf_s, _vsnprintf_s, _vsnprintf_s_l, _vsnwprintf_s, _vsnwprintf_s_l | Write formatted output using a pointer to a list of arguments |
| vsprintf, _vsprintf_l, vswprintf, _vswprintf_l, __vswprintf_l | vsprintf_s, _vsprintf_s_l, vswprintf_s, _vswprintf_s_l | Write formatted output using a pointer to a list of arguments |
| vsscanf, vswscanf | vsscanf_s, vswscanf_s | Read formatted data from a string |
| wcrtomb | wcrtomb_s | Convert a wide character into its multibyte character representation |
| wcsrtombs | wcsrtombs_s | Convert a wide character string to its multibyte character string representation |
| wcstombs, _wcstombs_l | wcstombs_s, _wcstombs_s_l | Convert a sequence of wide characters to a corresponding sequence of multibyte characters |
| wctomb, _wctomb_l | wctomb_s, _wctomb_s_l | Convert a wide character to the corresponding multibyte character |