![]() Write without automatic flushing used with tape drivesįilename can be a MATLABPATH relative partial pathname if the file is opened for reading only. Open file, or create new file, for reading and writing append data to the end of the file.Īppend without automatic flushing used with tape drives Open file, or create a new file, for reading and writing discard existing contents, if any. Open file, or create new file, for writing append data to the end of the file. Open file, or create new file, for writing discard existing contents, if any. Opens the file filename in the mode specified by permission. They are fid=1 (standard output) and fid=2 (standard error). Two file identifiers are automatically available and need not be opened. If fopen cannot open the file, it returns -1. You use the fid as the first argument to other file input/output routines. (On PCs, fopen opens files for binary read access.)įid is a scalar MATLAB integer, called a file identifier. = fopen(filename,permission,machineformat) Open a file or obtain information about open files Linux), this is not an issue, because on those platforms, there is no difference between text mode and binary mode.Fopen (MATLAB Functions) MATLAB Function Reference Therefore, the results you get will not be consistent. However, on Microsoft Windows, the characters \r\n (carriage return followed by line feed) will be translated to \n for text streams (but not for binary streams), so that the file size you get will count \r\n as two bytes, although you are only reading a single character ( \n) in text mode. That being said, on most common platforms, the posted code will work, if we assume that the data type long is large enough to represent the size of the file. The posted code is also not guaranteed to work on binary streams, because according to §7.21.9.2 ♣ of the ISO C11 standard, binary streams are not required to meaningfully support SEEK_END. There is no such guarantee for text streams. Only for binary streams is this value guaranteed to be the number of characters from the beginning of the file. The posted code is not guaranteed to work on text streams, because according to §7.21.9.4 ♢ of the ISO C11 standard, the value of the file position indicator returned by ftell contains unspecified information. In contrast to what other answers have suggested, the following code is not guaranteed to work: fseek( fp, 0, SEEK_END ) Įven if we assume that the data type long is large enough to represent the file size (which is questionable on some platforms, most notably Microsoft Windows), the posted code has the following problems: revert to platform-specific functions, such as stat on Linux or GetFileSize on Microsoft Windows.If you want a more efficient solution, then you will have to either In plain ISO C, there is only one way to determine the size of a file which is guaranteed to work: To read the entire file from the start, until you encounter end-of-file. It will going return 0 if the file is a pipe or stdin. Printf("%s: size=%ld", (unsigned long)f_size) Get the current position using ftell(3).Seek the file to the end using fseek(3).For now, we'll use the seek approach! Synopsis The ANSI C doesn't directly provides the way to determine the length of the file. Printf("%s: size=%ld\n", argv, info.st_size) If not Fat32 filesystem then use the 64bit version! Include the sys/stat.h header to use the function. The POSIX standard has its own method to get file size. See the "Using LFS" section of Large File Support in Linux for details. On 32-bit systems you should compile this with the option -D_FILE_OFFSET_BITS=64, otherwise off_t will only hold values up to 2 GB. If you want fsize() to print a message on error, you can use this: #include įprintf(stderr, "Cannot determine size of %s: %s\n", off_t is a signed type so this is possible. Returns -1 on error instead of 0, which would be ambiguous for an empty file.Corrected the struct stat definition, which was missing the variable name.Made the filename argument a const char.(Get a file descriptor from open(2), or fileno(FILE*) on a stdio stream). ![]() ![]() On Unix-like systems, you can use POSIX system calls: stat on a path, or fstat on an already-open file descriptor (POSIX man page, Linux man page). ![]()
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