SUMMARY
The following table lists the equivalent functions in .NET
for functions in the standard C library. Locate the standard C function in the
left column; the equivalent .NET function appears in the right column.
Note This is an approximate table. Some of the listed .NET functions
are similar to the standard C functions, but the .NET function listed may not
be an exact match. Also, if you use C++, replace the period character (
.) with two colons (
::).
If the function that you need is not listed in the
table, refer to the More
Information section of this article.
ARGUMENT ACCESS
STANDARD C FUNCTION .NET EQUIVALENT FUNCTION
---------------------------------------------------------------------------
va_arg,va_end,va_start ParamArray Attribute
---------------------------------------------------------------------------
BUFFER MANIPULATION
STANDARD C FUNCTIONS .NET EQUIVALENT FUNCTIONS
---------------------------------------------------------------------------
_memccpy,memcpy System.Buffer.BlockCopy,
System.String.Copy
memchr,wmemchr System.String.CopyTo
memcmp,memicmp System.Collections.Arraylist.BinarySearch
memmove System.String.Compare,
System.String.Equals
memset System.Buffer.SetByte,
System.Collections.Arraylist.Item
_swab n/a
---------------------------------------------------------------------------BYTE CLASSIFICATION
STANDARD C FUNCTIONS .NET EQUIVALENT FUNCTIONS
---------------------------------------------------------------------------
_isleadbyte n/a but see System.Globalization.CultureInfo
_ismbbalnum
_ismbbalpha
_ismbbgraph
_ismbbkalnum
_ismbbkana
_ismbbkprint
_ismbbkpunct
_ismbblead
_ismbbprint
_ismbbpunct
_ismbbtrail
_ismbslead
_ismbstrail
_mbbtype
_mbsbtype
---------------------------------------------------------------------------
CHARACTER CLASSIFICATION
STANDARD C FUNCTIONS .NET EQUIVALENT FUNCTIONS
---------------------------------------------------------------------------
isalnum, iswalnum System.Char.IsLetterOrDigit
_ismbcalnum n/a
isalpha, iswalpha, _ismbcalpha,
__isascii, iswascii System.Char.IsLetter
iscntrl, iswcntrl System.Char.IsControl
__iscsym, __iscsymf System.Char.IsSymbol
isdigit, iswdigit, _ismbcdigit System.Char.IsDigit
isgraph, iswgraph, _ismbcgraph n/a
islower, iswlower, _ismbclower System.Char.IsLower
_ismbchira n/a
_ismbckata n/a
_ismbclegal n/a
_ismbcl0 n/a
_ismbcl1 n/a
_ismbcl2 n/a
_ismbcsymbol n/a
isprint, iswprint, _ismbcprint n/a
ispunct, iswpunct, _ismbcpunct System.Char.IsPunctuation
isspace, iswspace, _ismbcspace System.Char.IsWhiteSpace
isupper, iswupper, _ismbcupper System.Char.IsUpper
iswctype System.Char.GetType
isxdigit, iswxdigit System.Char.IsNumber
mblen n/a
---------------------------------------------------------------------------
DATA CONVERSION
STANDARD C FUNCTIONS .NET EQUIVALENT FUNCTIONS
---------------------------------------------------------------------------
abs System.Math.Abs
atof System.Convert.ToDouble
atoi System.Convert.ToInt32,
System.Convert.ToUInt32
_atoi64 System.Convert.ToInt64,
System.Convert.ToUInt64
atol System.Convert.ToInt64,
System.Convert.ToUInt64
_ecvt System.Convert.ToString
_fcvt System.Convert.ToString
_gcvt System.Convert.ToString
_itoa, _i64toa, _itow, _i64tow System.Convert.ToString
labs System.Math.Abs
_ltoa, _ltow System.Convert.ToString
_mbbtombc n/a
_mbcjistojms n/a
_mbcjmstojis n/a
_mbctohira n/a
_mbctokata n/a
_mbctombb n/a
mbstowcs n/a
mbtowc n/a
strtod, wcstod System.Convert.ToDouble
strtol, wcstol System.Convert.ToInt64
strtoul, wcstoul System.Convert.ToUInt64
strxfrm, wcsxfrm System.Iformattable.ToString
__toascii
tolower, towlower, _mbctolower System.Char.ToLower
_tolower System.String.ToLower
toupper, towupper, _mbctoupper System.Char.ToUpper,
_toupper System.String.ToUpper
_ultoa, _ultow System.Convert.ToString
wcstombs n/a
wctomb n/a
_wtoi n/a
_wtol n/a
---------------------------------------------------------------------------DEBUG
STANDARD C FUNCTIONS .NET EQUIVALENT FUNCTIONS
---------------------------------------------------------------------------
_ASSERT, _ASSERTE System.Diagnostics.Debug.Assert
_CrtCheckMemory System.Diagnostics.PerformanceCounter
_CrtDbgReport System.Diagnostics.Debug.Write,
System.Diagnostics.Debug.Writeline,
System.Diagnostics.Debug.WriteIf,
System.Diagnostics.Debug.WriteLineIf
_CrtDoForAllClientObjects n/a
_CrtDumpMemoryLeaks n/a
_CrtIsValidHeapPointer n/a
_CrtIsMemoryBlock n/a
_CrtIsValidPointer n/a
_CrtMemCheckpoint n/a
_CrtMemDifference n/a
_CrtMemDumpAllObjectsSince n/a
_CrtMemDumpStatistics System.Diagnostics.PerformanceCounter
_CrtSetAllocHook n/a
_CrtSetBreakAlloc n/a
_CrtSetDbgFlag n/a
_CrtSetDumpClient n/a
_CrtSetReportFile n/a
_CrtSetReportHook n/a
_CrtSetReportMode n/a
_RPT[0,1,2,3,4] n/a
_RPTF[0,1,2,3,4] n/a
_calloc_dbg n/a
_expand_dbg n/a
_free_dbg n/a
_malloc_dbg n/a
_msize_dbg n/a
_realloc_dbg n/a
---------------------------------------------------------------------------DIRECTORY CONTROL
STANDARD C FUNCTIONS .NET EQUIVALENT FUNCTIONS
---------------------------------------------------------------------------
_chdir, _wchdir System.Environment.CurrentDirectory
_chdrive System.Environment.CurrentDirectory
_getcwd, _wgetcwd System.Environment.CurrentDirectory
_getdcwd, _wgetdcwd System.Environment.CurrentDirectory
_getdrive System.Environment.CurrentDirectory
_mkdir, _wmkdir System.IO.Directory.CreateDirectory,
System.IO.DirectoryInfo.CreateSubdirectory
_rmdir, _wrmdir System.IO.Directory.Delete
searchenv, _wsearchenv n/a
---------------------------------------------------------------------------ERROR HANDLING
STANDARD C FUNCTIONS .NET EQUIVALENT FUNCTIONS
---------------------------------------------------------------------------
assert macro n/a
_ASSERT, _ASSERTE macros System.Diagnostics.Debug.Assert
clearerr n/a
_eof n/a
feof n/a
ferror n/a
_RPT, _RPTF macros n/a
---------------------------------------------------------------------------
EXCEPTION HANDLING
STANDARD C FUNCTIONS .NET EQUIVALENT FUNCTIONS
---------------------------------------------------------------------------
_set_se_translator n/a
set_terminate n/a
set_unexpected n/a
terminate n/a
unexpected System.Exception
---------------------------------------------------------------------------
FILE-HANDLING ROUTINES (File Handle)
STANDARD C FUNCTIONS .NET EQUIVALENT FUNCTIONS
---------------------------------------------------------------------------
chsize System.IO.Stream.SetLength,
System.IO.FileStream.SetLength
_filelength System.IO.Stream.SetLength,
System.IO.FileStream.SetLength
_fstat, _fstati64 n/a
_isatty System.IO.Stream.CanWrite,
System.IO.FileStream.CanWrite
_locking System.IO.Stream.Lock,
System.IO.FileStream.Lock
_setmode see System.IO.BinaryReader,
System.IO.TextReader
---------------------------------------------------------------------------FILE-HANDLING ROUTINES (Path or File Name)
STANDARD C FUNCTIONS .NET EQUIVALENT FUNCTIONS
---------------------------------------------------------------------------
_access, _waccess System.IO.FileAccess
_chmod, _wchmod System.IO.File.SetAttributes,
System.Security.Permissions.FileIOPermission
_fullpath, _wfullpath System.IO.File.Create
_get_osfhandle n/a
_makepath, _wmakepath System.IO.File.Create
_mktemp, _wmktemp n/a
_open_osfhandle System.IO.FileStream.Handle
remove, _wremove System.IO.File.Remove
rename, _wrename System.IO.File.Move
_splitpath, _wsplitpath n/a
_stat, _stati64, System.IO.File.GetAttributes,
_wstat, _wstati64 System.IO.File.GetCreationTime,
System.IO.File.GetLastAccessTime,
System.IO.File.GetLastWriteTime
_umask System.IO.File.SetAttributes
_unlink, _wunlink System.IO.File.Remove
---------------------------------------------------------------------------FLOATING-POINT SUPPORT
STANDARD C FUNCTIONS .NET EQUIVALENT FUNCTIONS
---------------------------------------------------------------------------
abs System.Math.Abs
acos System.Math.Acos
asin System.Math.Asin
atan, atan2 System.Math.Atan, System.Math.Atan2
atof System.Convert.ToInt64,
System.ConvertToUInt64,
System.Convert.ToSingle,
System.Convert.ToDouble
Bessel functions
_cabs
ceil System.Math.Ceiling
_chgsign n/a
_clear87, _clearfp n/a
_control87, _controlfp n/a
_copysign n/a
cos, cosh System.Math.Cos, System.Math.Cosh
difftime System.DateTime.Subtract
div n/a
_ecvt System.Convert.ToString
exp System.Math.Exp
fabs System.Math.Abs
_fcvt System.Convert.ToString
_finite System.Double.IsInfinity
floor System.Math.Floor
fmod System.Math.IEEERemainder
_fpclass System.Double.IsInfinity,
System.Double.IsNegativeInfinity,
System.Double.IsPositiveInfinity,
System.Double.IsNan
_fpieee_flt n/a
frexp n/a
_gcvt System.Convert.ToString
_hypot n/a
_isnan System.Double.IsNan
labs System.Math.Abs
ldexp System.Math.Pow
ldiv n/a
log System.Math.Log
log10 System.Math.Log10
_logb
_lrotl, _lrotr n/a
_matherr n/a
__max System.Math.Max
__min System.Math.Min
modf n/a
nextafter
n/a
pow System.Math.Pow
printf, wprintf System.Console.Write,
System.Console.WriteLine
rand System.Random
_rotl, _rotr n/a
_scalb n/a
scanf, wscanf System.Console.Write,
System.Console.WriteLine
sin, sinh System.Math.Sin, System.Math.Sinh
sqrt System.Math.Sqrt
srand System.Random
_status87, _statusfp n/a
strtod System.Convert.ToDouble
tan, tanh System.Math.Tan, System.Math.Tanh
--------------------------------------------------------------------------INPUT AND OUTPUT
STANDARD C FUNCTIONS .NET EQUIVALENT FUNCTIONS
---------------------------------------------------------------------------
_open, fopen, System.IO.File.Open,
freopen, _fsopen System.IO.FileStream.Open
fwprintf, fwscanf, System.Stream.Write, System.Stream.WriteLine,
fgetwc, fputwc, fgetws, System.Console.Read,
fputws System.Console.ReadLine
clearerr n/a
fclose, _fcloseall System.IO.FileStream.Close,
System.IO.Stream.Close,
System.IO.BinaryReader.Close,
System.IO.BinaryWriter.Close,
System.IO.TextReader.Close,
System.IO.TextWriter.Close,
System.IO.StringReader.Close,
System.IO.StringWriter.Close,
System.IO.StreamReader.Close,
System.IO.StreamWriter.Close
_fdopen, wfdopen System.IO.FileStream.FileStream
feof System.IO.FileStream.File.Read
ferror n/a
fflush System.IO.FileStream.Flush
fgetc, fgetwc System.IO.FileStream.ReadByte
_fgetchar, _fgetwchar System.IO.BinaryReader.Read,
System.IO.TextReader.Read,
System.IO.StringReader.Read,
System.IO.StreamReader.Read
fgetpos, fgets, fgetws System.IO.FileStream.Seek
_fileno System.IO.FileStream.Handle
_flushall System.IO.FileStream.Flush,
System.IO.StreamWriter.Flush,
System.IO.TextWriter.Flush,
System.IO.StringWriter.Flush,
System.IO.BinaryWriter.Flush
fopen, _wfopen System.IO.File.Open
fprintf, fwprintf System.IO.TextWriter
fputc, fputwc,_fputchar,
_fputwchar n/a
fputs, fputws n/a
fread n/a
freopen, _wfreopen System.IO.File.Open
fscanf, fwscanf n/a
fseek n/a
fsetpos System.IO.FileStream.Seek
_fsopen, _wfsopen n/a
ftell n/a
fwrite n/a
getc, getwc n/a
getchar, getwchar n/a
gets, getws n/a
_getw n/a
printf, wprintf n/a
putc, putwc n/a
putchar, putwchar n/a
puts, _putws n/a
_putw n/a
rewind n/a
_rmtmp n/a
scanf, wscanf n/a
setbuf n/a
_setmaxstdio n/a
setvbuf n/a
_snprintf, _snwprintf n/a
swprintf n/a
sscanf, swscanf n/a
_tempnam, _wtempnam n/a
tmpfile n/a
tmpnam, _wtmpnam n/a
ungetc, ungetwc n/a
vfprintf, vfwprintf n/a
vprintf, vwprintf n/a
_vsnprintf, _vsnwprintf n/a
vsprintf, vswprintf n/a
---------------------------------------------------------------------------INTERNATIONALIZATION
STANDARD C FUNCTION .NET EQUIVALENT FUNCTION
---------------------------------------------------------------------------
Setlocale System.Globalization.CultureInfo
---------------------------------------------------------------------------
MEMORY ALLOCATION
STANDARD C FUNCTIONS .NET EQUIVALENT FUNCTIONS
---------------------------------------------------------------------------
_alloca n/a for all
calloc
_calloc_dbg
_expand
_expand_dbg
free
_free_dbg
_get_sbh_threshold
_heapadd
_heapchk
_heapmin
_heapset
_heapwalk
malloc new
_malloc_dbg
_msize
_msize_dbg
_query_new_handler
_query_new_mode
realloc
_realloc_dbg
_set_new_handler
_set_new_mode
_set_sbh_threshold
---------------------------------------------------------------------------
PROCESS AND ENVIRONMENT CONTROL
STANDARD C FUNCTIONS .NET EQUIVALENT FUNCTIONS
---------------------------------------------------------------------------
abort n/a
assert System.Diagnostics.Debug.Assert
_ASSERT, _ASSERTE macros System.Diagnostics.Debug.Assert
atexit System.Diagnostics.Process.AddOnExit
(see Process.OnExit)
_beginthread, _beginthreadex System.Threading.Thread.Start
_cexit,_c_exit System.Diagnostics.Process.CloseMainWindow
_cwait System.Diagnostics.Process.WaitForExit
_endthread, _endthreadex n/a
_execl, _wexecl n/a
_execle, _wexecle n/a
_execlp, _wexeclp n/a
_execlpe, _wexeclpe n/a
_execv, _wexecv n/a
_execve, _wexecve n/a
_execvp, _wexecvp n/a
_execvpe, _wexecvpe System.Diagnostics.Process,
System.Diagnostics.ProcessInfo
exit,_exit System.Diagnostics.Process.Kill
getenv, _wgetenv System.Environment.GetEnvironmentVariable
_getpid System.Diagnostics.Process.Id
longjmp n/a
_onexit System.Diagnostics.Process.OnExit
_pclose n/a
perror, _wperror n/a
_pipe n/a
_popen, _wpopen n/a
_putenv, _wputenv n/a
raise n/a
setjmp n/a
signal n/a
_spawnl, _wspawnl n/a
_spawnle, _wspawnle n/a
_spawnlp, _wspawnlp n/a
_spawnlpe, _wspawnlpe n/a
_spawnv, _wspawnv n/a
_spawnve, _wspawnve n/a
_spawnvp, _wspawnvp n/a
_spawnvpe, _wspawnvpe n/a
system, _wsystem System.Diagnostics.ProcessStartInfo,
System.Diagnostics.Process
---------------------------------------------------------------------------SEARCH AND SORTING
STANDARD C FUNCTIONS .NET EQUIVALENT FUNCTIONS
---------------------------------------------------------------------------
bsearch System.Collections.ArrayList.BinarySearch
_lfind System.Collections.ArrayList.Contains
_lsearch n/a
qsort System.Collections.ArrayList.Sort
---------------------------------------------------------------------------
STRING MANIPULATION
STANDARD C FUNCTIONS .NET EQUIVALENT FUNCTIONS
---------------------------------------------------------------------------
mbscoll, _mbsicoll, System.String.Compare
_mbsncoll, _mbsnicoll
_mbsdec, _strdec, _wcsdec n/a
_mbsinc, _strinc, _wcsinc n/a
_mbslen n/a
_mbsnbcat n/a
_mbsnbcmp n/a
_mbsnbcnt n/a
_mbsnbcpy n/a
_mbsnbicmp n/a
_mbsnbset n/a
_mbsnccnt n/a
_mbsnextc, _strnextc, _wcsnextc n/a
_mbsninc. _strninc, _wcsninc n/a
_mbsspnp, _strspnp, _wcsspnp n/a
_mbstrlen n/a
sprintf, _stprintf System.Console.Write,
System.Console.Writeline
strcat, wcscat, _mbscat System.String.Concat
strchr, wcschr, _mbschr n/a
strcmp, wcscmp, _mbscmp n/a
strcoll, wcscoll,
_stricoll, _wcsicoll,
_strncoll, _wcsncoll n/a
_strnicoll, _wcsnicoll System.String.Compare
strcpy, wcscpy, _mbscpy System.String.Copy
strcspn, wcscspn, _mbscspn System.String.Substring
_strdup, _wcsdup, _mbsdup System.String.Clone
strerror,_strerror System.Exception.Message
strftime, wcsftime System.Convert.ToString
_stricmp, _wcsicmp, _mbsicmp System.String.Compare
strlen, wcslen, System.String.Length
_mbslen, _mbstrlen
_strlwr, _wcslwr, _mbslwr System.String.ToLower
strncat, wcsncat, _mbsncat System.String.Concat
strncmp, wcsncmp, _mbsncmp System.String.Compare
strncpy, wcsncpy, _mbsncpy System.String.Copy
wcsncpy, _mbsncpy System.String.Copy
_strnicmp, _wcsnicmp, _mbsnicmp System.String.Compare
_strnset, _wcsnset, _mbsnset System.String.Replace
strpbrk, wcspbrk, _mbspbrk n/a
strrchr, wcsrchr,_mbsrchr n/a
_strrev, _wcsrev,_mbsrev n/a
_strset, _wcsset, _mbsset n/a
strspn, wcsspn, _mbsspn System.String.Substring
strstr, wcsstr, _mbsstr n/a
strtok, wcstok, _mbstok n/a
_strupr, _wcsupr, _mbsupr System.String.ToUpper
strxfrm, wcsxfrm n/a
vsprintf, _vstprint n/a
---------------------------------------------------------------------------SYSTEM CALLS
STANDARD C FUNCTIONS .NET EQUIVALENT FUNCTIONS
---------------------------------------------------------------------------
_findclose System.IO.Directory.GetFiles,
_findfirst, _findfirsti64 System.IO.DirectoryInfo.GetFiles
_wfindfirst, _wfindfirsti64 System.IO.DirectoryInfo.GetFileSystemInfos
_findnext, _findnexti64 n/a
_wfindnext, _wfindnexti64 n/a
---------------------------------------------------------------------------TIME MANAGEMENT
STANDARD C FUNCTIONS .NET EQUIVALENT FUNCTIONS
---------------------------------------------------------------------------
asctime, _wasctime System.DateTime.ToLongDateString,
System.DateTime.ToLongTimeString,
System.DateTime.ToShortDateString,
System.DateTime.ToShortTimeString,
System.DateTime.ToString
clock n/a
ctime, _wctime System.DateTime.GetDateTimeFormats,
System.DateTime.ToString,
System.DateTime.ToLongTimeString,
System.DateTime.ToShortTimeString
difftime System.DateTime.Subtract
_ftime System.DateTime.Now
_futime System.IO.File.SetLastAccessTime,
System.IO.File.SetLastWriteTime,
System.IO.File.SetCreationTime
gmtime System.DateTime.UtcNow,
System.DateTime.ToUniversalTime
localtime System.DateTime.ToLocalTime
mktime System.DateTime.DateTime
_strdate, _wstrdate System.DateTime.Parse
strftime, wcsftime, System.DateTime.ToLongDateString,
_strtime, _wstrtime System.DateTime.ToLongTimeString,
System.DateTime.ToShortDateString,
System.DateTime.ToShortTimeString,
System.DateTime.ToString
time n/a
_tzset n/a
_utime, _wutime n/a