When append mode is used, the fopen fails. See z/OS XL C/C Programming Guide for more information about fopen default attributes. Samethread: This parameter specifies that I/O operations against the stream are restricted to the thread in which the stream was opened. The library will not lock the stream in a multithread environment.
-->Opens a file. These versions of fopen, _wfopen have security enhancements, as described in Security Features in the CRT.
pFile
A pointer to the file pointer that will receive the pointer to the opened file.
filename
Filename.
mode
Type of access permitted.
Zero if successful; an error code on failure. See errno, _doserrno, _sys_errlist, and _sys_nerr for more information about these error codes.
| pFile | filename | mode | Return Value | Contents of pFile |
|---|---|---|---|---|
| NULL | any | any | EINVAL | unchanged |
| any | NULL | any | EINVAL | unchanged |
| any | any | NULL | EINVAL | unchanged |
Files that are opened by fopen_s and _wfopen_s are not sharable. If you require that a file be sharable, use _fsopen, _wfsopen with the appropriate sharing mode constant—for example, _SH_DENYNO for read/write sharing.
The fopen_s function opens the file that's specified by filename. _wfopen_s is a wide-character version of fopen_s; the arguments to _wfopen_s are wide-character strings. _wfopen_s and fopen_s behave identically otherwise.
fopen_s accepts paths that are valid on the file system at the point of execution; UNC paths and paths that involve mapped network drives are accepted by fopen_s as long as the system that's executing the code has access to the share or mapped network drive at the time of execution. When you construct paths for fopen_s, don't make assumptions about the availability of drives, paths, or network shares in the execution environment. You can use either forward slashes (/) or backslashes () as the directory separators in a path.
These functions validate their parameters. If pFile, filename, or mode is a null pointer, these functions generate an invalid parameter exception, as described in Parameter Validation.
Always check the return value to see if the function succeeded before you perform any further operations on the file. If an error occurs, the error code is returned and the global variable errno is set. For more information, see errno, _doserrno, _sys_errlist, and _sys_nerr.
Download cooking academy 1 torent. By default, this function's global state is scoped to the application. To change this, see Global state in the CRT.
fopen_s supports Unicode file streams. To open a new or existing Unicode file, pass a ccs flag that specifies the desired encoding to fopen_s:
fopen_s(&fp, 'newfile.txt', 'rw, ccs=encoding');
Allowed values of encoding are UNICODE, UTF-8, and UTF-16LE. If there no value is specified for encoding, fopen_s Mac os x 10.7.5 boot camp windows 7. uses ANSI encoding.
If the file already exists and is opened for reading or appending, the Byte Order Mark (BOM), if present in the file, determines the encoding. The BOM encoding takes precedence over the encoding that's specified by the ccs flag. The ccs encoding is only used when no BOM is present or if the file is a new file.
Note
BOM-detection only applies to files that are opened in Unicode mode; that is, by passing the ccs flag.
The following table summarizes the modes for various ccs flags that are given to fopen_s and for Byte Order Marks in the file.
| ccs flag | No BOM (or new file) | BOM: UTF-8 | BOM: UTF-16 |
|---|---|---|---|
| UNICODE | UTF-16LE | UTF-8 | UTF-16LE |
| UTF-8 | UTF-8 | UTF-8 | UTF-16LE |
| UTF-16LE | UTF-16LE | UTF-8 | UTF-16LE |
Files that are opened for writing in Unicode mode have a BOM written to them automatically.
If mode is 'a, ccs=encoding', fopen_s first tries to open the file with both read access and write access. If successful, the function reads the BOM to determine the encoding for the file; if unsuccessful, the function uses the default encoding for the file. In either case, fopen_s then re-opens the file with write-only access. (This applies to a mode only, not a+.)
| TCHAR.H routine | _UNICODE & _MBCS not defined | _MBCS defined | _UNICODE defined |
|---|---|---|---|
| _tfopen_s | fopen_s | fopen_s | _wfopen_s |
The character string mode specifies the kind of access that's requested for the file, as follows.
| mode | Access |
|---|---|
| 'r' | Opens for reading. If the file does not exist or cannot be found, the fopen_s call fails. |
| 'w' | Opens an empty file for writing. If the given file exists, its contents are destroyed. |
| 'a' | Opens for writing at the end of the file (appending) without removing the end-of-file (EOF) marker before new data is written to the file. Creates the file if it does not exist. |
| 'r+' | Opens for both reading and writing. The file must exist. |
| 'w+' | Opens an empty file for both reading and writing. If the file exists, its contents are destroyed. |
| 'a+' | Opens for reading and appending. The appending operation includes the removal of the EOF marker before new data is written to the file. The EOF marker is not restored after writing is completed. Creates the file if it does not exist. |
When a file is opened by using the 'a' or 'a+' access type, all write operations occur at the end of the file. The file pointer can be repositioned by using fseek or rewind, but it's always moved back to the end of the file before any write operation is carried out so that existing data cannot be overwritten.
The 'a' mode does not remove the EOF marker before appending to the file. After appending has occurred, the MS-DOS TYPE command only shows data up to the original EOF marker and not any data that's appended to the file. The 'a+' mode does remove the EOF marker before appending to the file. After appending, the MS-DOS TYPE command shows all data in the file. The 'a+' mode is required for appending to a stream file that is terminated by using the CTRL+Z EOF marker.
When the 'r+', 'w+', or 'a+' access type is specified, both reading and writing are allowed. (The file is said to be open for 'update'.) However, when you switch from reading to writing, the input operation must encounter an EOF marker. If there is no EOF, you must use an intervening call to a file-positioning function. The file-positioning functions are fsetpos, fseek, and rewind. When you switch from writing to reading, you must use an intervening call to either fflush or to a file-positioning function.
In addition to the above values, the following characters can be included in mode to specify the translation mode for newline characters:
| mode modifier | Translation mode |
|---|---|
| t | Open in text (translated) mode. |
| b | Open in binary (untranslated) mode; translations involving carriage-return and line feed characters are suppressed. |
In text (translated) mode, CTRL+Z is interpreted as an end-of-file character on input. In files opened for reading/writing with 'a+', fopen_s checks for a CTRL+Z at the end of the file and removes it, if possible. This is done because using fseek and ftell to move within a file that ends with a CTRL+Z, may cause fseek to behave improperly near the end of the file.
Also, in text mode, carriage return-line feed combinations are translated into single line feeds on input, and line feed characters are translated to carriage return-line feed combinations on output. When a Unicode stream-I/O function operates in text mode (the default), the source or destination stream is assumed to be a sequence of multibyte characters. Therefore, the Unicode stream-input functions convert multibyte characters to wide characters (as if by a call to the mbtowc function). For the same reason, the Unicode stream-output functions convert wide characters to multibyte characters (as if by a call to the wctomb function).
If t or b is not given in mode, the default translation mode is defined by the global variable _fmode. If t or b is prefixed to the argument, the function fails and returns NULL.
For more information about using text and binary modes in Unicode and multibyte stream-I/O, see Text and Binary Mode File I/O and Unicode Stream I/O in Text and Binary Modes.
| mode modifier | Behavior |
|---|---|
| c | Enable the commit flag for the associated filename so that the contents of the file buffer are written directly to disk if either fflush or _flushall is called. |
| n | Reset the commit flag for the associated filename to 'no-commit.' This is the default. It also overrides the global commit flag if you link your program with COMMODE.OBJ. The global commit flag default is 'no-commit' unless you explicitly link your program with COMMODE.OBJ (see Link Options). |
| N | Specifies that the file is not inherited by child processes. |
| S | Specifies that caching is optimized for, but not restricted to, sequential access from disk. |
| R | Specifies that caching is optimized for, but not restricted to, random access from disk. |
| T | Specifies a file as temporary. If possible, it is not flushed to disk. |
| D | Specifies a file as temporary. It is deleted when the last file pointer is closed. |
| ccs=encoding | Specifies the encoded character set to use (one of UTF-8, UTF-16LE, or UNICODE) for this file. Leave unspecified if you want ANSI encoding. |
Valid characters for the mode string used in fopen_s and _fdopen correspond to oflag arguments used in _open and _sopen, as follows.
| Characters in mode string | Equivalent oflag value for _open/_sopen |
|---|---|
| a | _O_WRONLY_O_APPEND (usually _O_WRONLY_O_CREAT ** _O_APPEND**) |
| a+ | _O_RDWR_O_APPEND (usually _O_RDWR_O_APPEND_O_CREAT ) |
| r | _O_RDONLY |
| r+ | _O_RDWR |
| w | _O_WRONLY (usually _O_WRONLY_O_CREAT ** _O_TRUNC**) |
| w+ | _O_RDWR (usually _O_RDWR_O_CREAT_O_TRUNC) |
| b | _O_BINARY |
| t | _O_TEXT |
| c | None |
| n | None |
| S | _O_SEQUENTIAL |
| R | _O_RANDOM |
| T | _O_SHORTLIVED |
| D | _O_TEMPORARY |
| ccs=UNICODE | _O_WTEXT |
| ccs=UTF-8 | _O_UTF8 |
| ccs=UTF-16LE | _O_UTF16 |
If you are using rb mode, won't need to port your code, and expect to read a lot of the file and/or don't care about network performance, memory mapped Win32 files might also be an option.
| Function | Required header |
|---|---|
| fopen_s | <stdio.h> |
| _wfopen_s | <stdio.h> or <wchar.h> |
For additional compatibility information, see Compatibility.
All versions of the C run-time libraries.
The c, n, and tmode options are Microsoft extensions for fopen_s and _fdopen and should not be used where ANSI portability is desired.
Stream I/O
fclose, _fcloseall
_fdopen, _wfdopen
ferror
_fileno
freopen, _wfreopen
_open, _wopen
_setmode