If the file already exists and is opened for reading or appending, then any byte order mark (BOM) in the file determines the encoding. You're responsible for any required encoding translation. To read or write data that's stored in your program as UTF-8, use a text or binary file mode instead of a Unicode mode.
An attempt to read or write an odd number of bytes in Unicode mode causes a parameter validation error. The file's UTF-8-encoded content is translated into UTF-16 when it's read. If the file is encoded as UTF-8, then UTF-16 data is translated into UTF-8 when it's written.
Functions that write to a file opened in Unicode mode expect buffers that contain UTF-16 data stored as type wchar_t. When a file is opened in Unicode mode, input functions translate the data that's read from the file into UTF-16 data stored as type wchar_t. To open a Unicode file, pass a ccs=encoding flag that specifies the desired encoding to fopen, as follows.įILE *fp = fopen("newfile.txt", "rt+, ccs=UTF-8") Īllowed values for ccs encoding are UNICODE, UTF-8, and UTF-16LE. Unicode supportįopen supports Unicode file streams. To change it, see Global state in the CRT. For more information, see errno, _doserrno, _sys_errlist, and _sys_nerr.īy default, this function's global state is scoped to the application. If an error occurs, the global variable errno is set, and may be used to obtain specific error information. You can use either forward slashes ( /) or backslashes ( \) as the directory separators in a path.Īlways check the return value to see whether the pointer is NULL before you perform any other operations on the file. When you construct paths for fopen, make sure that drives, paths, or network shares are available in the execution environment.
Fopen find file size code#
Just using _wfopen doesn't affect the coded character set that's used in the file stream.įopen accepts paths that are valid on the file system at the point of execution fopen accepts UNC paths and paths that involve mapped network drives as long as the system that executes the code has access to the share or mapped drive at the time of execution. Otherwise, _wfopen and fopen behave identically. _wfopen is a wide-character version of fopen the _wfopen arguments are wide-character strings. You can use the AreFileApisANSI function to determine whether filename is interpreted using the ANSI or the system default OEM codepage.
Fopen find file size windows#
In Windows Desktop applications, it can be changed to the OEM codepage ( CP_OEMCP) by using the SetFileApisToOEM function. By default, a narrow filename string is interpreted using the ANSI codepage ( CP_ACP). The fopen function opens the file specified by filename. If execution is allowed to continue, these functions return NULL and set errno to EINVAL.įor more information, see errno, _doserrno, _sys_errlist, and _sys_nerr. If filename or mode is NULL or an empty string, these functions trigger the invalid parameter handler, which is described in Parameter validation. Return valueĮach of these functions returns a pointer to the open file. More-secure versions of these functions that perform more parameter validation and return error codes are available see fopen_s, _wfopen_s. It is the real code, it is a little odd situation: // reading png bytes from fileįILE *fp = fopen("./test/resources/RGBA_8bits.Opens a file. I could also before checking with feof() do something like this fread(NULL, 1, 1, fp) I am asking about this because when I add +1 then the number of bytes read by fread() is really -1 byte less, and as the last byte is inserted 00 byte. Should I always add this +1 value to this size to read all bytes from binary file or there is some hidden reason that this isn't reading to EOF? struct stat finfo It returns false! So I need to read (st_size + 1) and only than all bytes have been read and feof() works correctly.
I come to this conclusion when I used feof() function to check if there really nothing left in FILE *.
If I get the file size's in this way, then allocate a buffer of that size and read exactly that size of bytes there seems to be one byte left over. Now I am considering what the st_size field really means and how should I use it. So I intend to use fstat() function and struct stat. I consider reading file of unknown size that I know doesn't change size in the meantime.
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