![]() ![]() Linux), this is not an issue, because on those platforms, there is no difference between text mode and binary mode. Therefore, the results you get will not be consistent. The stream is positioned at the beginning of the. The argument mode points to a string beginning with one of the following sequences (possibly followed by additional characters, as described below): r Open text file for reading. 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. The fopen () function opens the file whose name is the string pointed to by pathname and associates a stream with it. 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). ftell – We will use this function to calculate the size.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).fseek – We will this function to move the file from its current position to a new position.The file pointer is passed as a parameter to the data type. fclose – We will use this to closing the file.Here,we will send filename and mode as a parameter. This function will create a new file if the mentioned file name will not exist. We will declare a file pointer and will use fopen() function. fopen – We will open the file in read mode.In addition, file handling enables us to create, update, read and delete the files stored on the local file system. In this code, we will use file handling to enhance the code. Moreover, we will use many functions like fopen,fclose,fseek,ftell to calculate the size. From this, we will calculate the size of file in bytes. To get the size of a file in C++, we will use file handling here. When we write a file in file system, it may consume the data more than the file requires. File size is a measure of how much data a files contains. ![]()
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