std::experimental::filesystem::file_size (3) - Linux Man Pages
Defined in header <experimental/filesystem>
std::uintmax_t file_size( const path& p ); (1) (filesystem TS)
std::uintmax_t file_size( const path& p, error_code& ec );
Returns the size of the regular file p, determined as if by reading the st_size member of the structure obtained by POSIX stat (symlinks are followed)
Attempting to determine the size of a directory (as well as any other file that is not a regular file or a symlink) is treated as an error.
The non-throwing overload returns returns -1 on errors.
p - path to examine
ec - out-parameter for error reporting in the non-throwing overload
The size of the file, in bytes.
The overload that does not take a error_code& parameter throws filesystem_error on underlying OS API errors, constructed with p as the first argument and the OS error code as the error code argument. std::bad_alloc may be thrown if memory allocation fails. The overload taking a error_code& parameter sets it to the OS API error code if an OS API call fails, and executes ec.clear() if no errors occur. This overload has
// Run this code